Comparison of foveal thickness measured with the retinal thickness analyzer and optical coherence tomography

Safety of accelerated corneal collagen cross-linking in keratoconus patients on the basis of macular segmentation

PURPOSE

To investigate the safety of accelerated corneal collagen cross-linking (A-CXL) in patients with keratoconus on the basis of thickness analysis measurements of retinal layers and retinal morphology.

STUDY DESIGN

This was a retrospective and comparative study.

METHODS

The study included 64 eyes of 32 patients with keratoconus disease. One eye of the patients underwent A-CXL for progressive keratoconus (CXL group) and the fellow eye was followed due to the absence of progression. Patients with at least 1-year follow-up after A-CXL were included. Keratometry, pachymetry and corrected-distance visual acuity (CDVA) levels of the patients were compared. The segmentation analysis of the individual retinal layers of the eyes with (CXL group) and without CXL (no CXL group) was compared with spectral domain-optical coherence tomography automatic segmentation program at baseline and at the last follow-up. The thickness of the retinal nerve fiber layer, ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer and retina pigment epithelium layer in the central 1-mm subfield defined by the ETDRS was analyzed.

RESULTS

The mean age of keratoconus patients was 23.9 ± 5.4 years, patients were more likely to be male (21/11, 65.6%), and the mean follow-up duration was 13.9 ± 1.5 months. When keratometry, pachymetry and CDVA levels were compared, only a significant difference was found between CDVA at the last follow-up (0.21 vs. 0.11 LogMAR). No significant difference was observed in neither retinal morphology nor segmentation of individual retinal layers at baseline and at the final evaluation (P > 0.05).

CONCLUSIONS

It has been observed that the A-CXL protocol did not cause a significant change in both retinal layer thickness and macular morphology.

An Intelligent Optical Coherence Tomography-based System for Pathological Retinal Cases Identification and Urgent Referrals

Purpose

This study aimed to develop an automated system with artificial intelligence algorithms to comprehensively identify pathologic retinal cases and make urgent referrals.

Methods

To build and test the intelligent system, this study obtained 28,664 optical coherence tomography (OCT) images from 2254 patients in the Eye and ENT Hospital of Fudan University (EENT Hospital) and Shanghai Tenth People's Hospital (TENTH Hospital). We applied a deep learning model with an adapted feature pyramid network to detect 15 categories of retinal pathologies from OCT images as common signs of various retinal diseases. Subsequently, the pathologies detected in the OCT images and thickness features extracted from retinal thickness measurements were combined for urgent referral using the random forest tool.

Results

The retinal pathologies detection model had a sensitivity of 96.39% and specificity of 98.91% from the EENT Hospital test dataset, whereas those from the TENTH Hospital test dataset were 94.89% and 98.76%, respectively. The urgent referral model achieved accuracies of 98.12% and 98.01% from the EENT Hospital and TENTH Hospital test datasets, respectively.

Conclusions

An intelligent system capable of automatically identifying pathologic retinal cases and offering urgent referrals was developed and demonstrated reliable performance with high sensitivity, specificity, and accuracy.

Translational Relevance

This intelligent system has great value and practicability in communities where exist increasing cases of retinal disease and a lack of ophthalmologists.

Posterior pole retinal thickness distribution pattern in keratoconus

PURPOSE

To evaluate the pattern of retinal thickness distribution in patients with keratoconus (KCN) and its correlation with disease severity.

METHODS

For this cross-sectional cohort study, the study subjects with documented keratoconus and normal eyes were prospectively enrolled. All subjects had anterior segment (Pentacam HR) and posterior segment (Spectralis) imaging. Posterior segment imaging by optical coherence tomography included the posterior pole asymmetry analysis map. Data were analyzed with multiple linear regression models and correlation tests to examine the mean and variance of the measured thickness of the retina and its distribution relative to the presence and severity of KCN.

RESULTS

A total of 24 subjects with keratoconus (48 eyes) and 14 normal subjects (28 eyes) enrolled in this study. The posterior pole retinal thickness, both superior and inferior hemifields, as well as the overall retinal thickness in KCN patients was greater than the control group. There was a direct correlation between the overall retinal thickness of the posterior pole and the severity of KCN (R² = 0.422, P < 0.001). However, the variability of the retinal thickness showed no difference between KCN-afflicted and healthy eyes.

CONCLUSION

Although KCN is a disease of the anterior segment of the eye, we found an orderly increase in posterior pole retinal thickness that is correlated with the severity of disease in KCN eyes compared to control. These findings suggest that the retina may maintain some degree of plasticity to respond to the degraded optical system of the eye.

Assessment of Macular Parameter Changes in Patients with Keratoconus Using Optical Coherence Tomography

Keratoconus is typically diagnosed through changes at the anterior ocular surface. However, we wished to assess if macular parameter changes might also occur in these patients. We assessed posterior changes through the use of optical coherence tomography and compared to a nonkeratoconus patient group. All subjects underwent clinical examination including macular thickness measurements. The generalized estimation equation model was used to estimate the means and compare the differences in various measurements between keratoconus and nonkeratoconus patients. A total of 129 keratoconus eyes of 67 cases and 174 nonkeratoconus eyes of 87 controls were analysed. Keratoconus individuals presented with a significantly greater mean retinal thickness in the central fovea, inner, and outer macula compared to the nonkeratoconus group (p < 0.05). In addition, individuals presenting with the early signs of keratoconus had significantly greater inner and outer macular volume compared to the nonkeratoconus group (p < 0.05). This study indicates the retina appears to thicken at the fovea and macula and had increased macular volume in keratoconus individuals compared to nonkeratoconus individuals. Thus we posit that structural retinal changes exist in keratoconus eyes that are additional to those typically seen in the anterior segment.

Evaluation of Central Macular Thickness and Retinal Nerve Fiber Layer Thickness using Spectral Domain Optical Coherence Tomography in a Tertiary Care Hospital

Purpose: To evaluate the normative data of macular thickness and retinal nerve fiber layer thickness (RNFL) among normal subjects using spectral domain optical coherence tomography (OCT).

Materials and methods: Normal subjects presenting to a tertiary medical hospital were included in the study. All patient underwent clinical examination followed by study of macular thickness and RN FL thick ness by spectral domain Topc on OCT. The data was collected and analyzed for variations in gender and age. The data was also compared with available literature.

Results: Total numbers of patients enrolled in the study were 154 (308 eyes). Numbers of males were 79 (158 eyes) and numbers of females were 75 (150 eyes). The mean age among males was 42.67 ± 12.15 years and mean age among females was 42.88 ± 11.73 years.

Overall the mean mac ular thickness (central 1 mm zone) with SD - OCT was 241.75 ± 17.3 microns. The mean macular volume was 7.6 cu. mm ± 0.33. On analysis of the RNFL thickness, we observed that the RNFL was thickest in the inferior quadrant (138.58) followed by superior (122.30) nasal (116.32) and temporal quadrant (73.04).

Gender-wise comparison of the data revealed no statistically significant difference for age, macular thickness parameters, volume and RFNL values except outer temporal thickness among males and females. No age-related difference was noted in the above parameters. On comparison with available norma tive data from India and elsewhere, we found significant variations with different machines.

Conclusion: The study is the first to provide normative data using SD-OCT from central India. The data from spectral domain OCT correlated well with the values obtained from similar studies with SD - OCT. Values obtained from time domain OCT machines are different and are not comparable.

How to cite this article: Agarwal P, Saini VK, Gupta S, Sharma A. Evaluation of Central Macular Thickness and Retinal Nerve Fiber Layer Thickness using Spectral Domain Optical

Coherence Tomography in a Tertiary Care Hospital. J Curr Glaucoma Pract 2014;8(2):75-81.

Repeatability and reproducibility of retinal thickness measurements with spectral-domain optical coherence tomography using different scan parameters

PURPOSE

To evaluate repeatability (test-retest) and reproducibility of retinal thickness measurements using spectral-domain optical coherence tomography with different densities of A-scans per B-scan and different frames per B-scan for real-time averaging.

METHODS

Twelve healthy subjects were analyzed by spectral-domain optical coherence tomography. Raster lines analysis with 19 B-scans over the examined area centered on the macula was performed. Images were acquired both in standard-density (768 A-scans/B-scan) and high-density (1,536 A-scans/B-scan) modalities. Moreover, images were acquired using 2 and 20 frames/B-scan for real-time averaging. Each analysis was repeated twice to test for repeatability.

RESULTS

Intersession repeatability was good for all studied analysis protocols, with Lin concordance correlation coefficient values ranging between 0.88 and 1.00. Reproducibility assessment showed consistent retinal thickness measurements using variable scan density, with Bland-Altman limits of agreement of -6 μm to 6 μm in the central area. Reproducibility assessment showed consistent retinal thickness measurements using different number of frames used in the real-time averaging process, with Bland-Altman limits of agreement of -8 μm to 4 μm in the central area.

CONCLUSION

Spectral-domain optical coherence tomography is a very reliable tool for central retinal thickness assessment. Changes in the number of A-scans/B-scan and in frames used for real-time averaging do not affect repeatability and reproducibility.

Reproducibility of retinal thickness measurements on normal and pathologic eyes by different optical coherence tomography instruments

PURPOSE

To compare retinal thickness measurements produced by different time-domain and spectral-domain optical coherence tomography (TD-OCT and SD-OCT) devices when imaging normal and pathologic eyes.

DESIGN

Prospective, observational study in an academic institutional setting.

METHODS

A total of 110 eyes were imaged by 6 different OCT devices: Stratus and Cirrus (Carl Zeiss Meditec Inc), Spectralis HRA+OCT (Heidelberg Engineering), RTVue-100 (Optovue Inc), SDOCT Copernicus HR (Optopol Technology S.A.), and 3D OCT-1000 (Topcon Corporation). Eyes were normal or affected by different pathologies of the retina, including exudative and nonexudative age-related macular degeneration, epiretinal membrane, cystoid macular edema, and macular hole. For each instrument we used standard analysis protocols for macular thickness evaluation. Mean retinal thickness values between the instruments in the ETDRS central circular 1000-μm-diameter areas and in the ETDRS midperipheral circular 3000-μm-diameter areas were compared.

RESULTS

The 6 different devices produced measurements that differ in variance (Bartlett test, P = .006), and mean values (Friedman test, P < .001). Bland-Altman analysis revealed that the limits of agreement for all the comparisons were not acceptable. Regression was calculated and it was elaborated into a conversion table, despite a high standard error for both intercepts and slope conversion values.

CONCLUSIONS

This study suggests that retinal thickness measurements obtained with various OCT devices are different beyond clinical practice tolerance, according to Bland-Altman analysis. Furthermore, regression analysis reveals high standard error values. These differences appear to be primarily attributable to the analysis algorithms used to set retinal inner and outer boundaries.

Efficacy and tolerability of preservative-free and preserved diclofenac and preserved ketorolac eyedrops after cataract surgery

PURPOSE

To compare the anti-inflammatory efficacy and subjective tolerability of preservative-free and preserved diclofenac 0.1% and preserved ketorolac 0.5% eye drops for prophylaxis and management of inflammation after cataract surgery.

DESIGN

Prospective, randomized, investigator-masked, parallel-group, comparative clinical trial.

METHODS

One hundred two patients who underwent small-incision phacoemulsification cataract surgery in an institutional setting were assigned randomly to receive preservative-free diclofenac sodium 0.1% (Voltaren ophtha SDU; Novartis Pharma), preserved diclofenac sodium 0.1% (Voltaren ophtha; Novartis Pharma), or preserved ketorolac tromethamine 0.5% (Acular; Pharm Allergan) eyedrops 4 times daily for 4 weeks after surgery. During the 1-month follow-up, anterior chamber flare and mean foveal thickness were evaluated for objective comparison of the anti-inflammatory effect. Ocular tolerability was assessed by observer-based grading of conjunctival hyperemia and ocular discomfort, as well as obtaining subjective ratings of ocular tolerability on a visual analog scale. Distance and near visual acuity and intraocular pressure served as safety measures.

RESULTS

All 3 formulations demonstrated equal anti-inflammatory efficacy as measured by reduction of anterior chamber flare after surgery and prevention of postoperative macular edema. Patients treated with preservative-free diclofenac eyedrops reported significantly better subjective tolerability values (P = .001), were classified as having less ocular discomfort (P < .001), and experienced earlier reduction of postoperative conjunctival hyperemia (P = .029).

CONCLUSIONS

Anti-inflammatory efficacy was comparable for all 3 agents. However, preservative-free diclofenac 0.1% eyedrops exhibited a significantly better postoperative subjective and objective tolerability when compared with preserved eyedrops containing ketorolac or diclofenac.

Comparison of macular thickness between Cirrus HD-OCT and Stratus OCT

BACKGROUND AND OBJECTIVE

To compare macular thicknesses in healthy subjects measured with spectral domain optical coherence tomography (SD-OCT) (Cirrus; Carl Zeiss Meditec, Inc., Dublin, CA) with measurements using time domain (TD-OCT) (Stratus; Carl Zeiss Meditec, Inc.).

PATIENTS AND METHODS

Macular thickness was measured five times in the same eye of 10 healthy subjects with both Cirrus and Stratus to assess reliability and then once in the same eye of 50 healthy subjects with both Cirrus and Stratus to compare the average obtained by each device.

RESULTS

Using TD-OCT, the coefficient of variations (CV) of the macular thicknesses within a 1-mm central area ranged from 0.7% to 3.3% (mean, 1.33%); with SD-OCT, the range was 0.2% to 1.3% (mean, 0.66%). The mean CV with SD-OCT was significantly smaller than with TD-OCT (P < .05). The average macular thicknesses with TD-OCT and SD-OCT were 197.2 +/- 17.8 microm and 257.6 +/- 19.6 microm, respectively. However, the correlation was significant (correlation coefficient, 0.916, P<.001).

CONCLUSION

Cirrus showed better reliability than Stratus. Using SD-OCT, the macula was 60-microm thicker than when measured with TD-OCT. Attention should be given to comparing data obtained using different OCT machines.

Prospective comparison of cirrus and stratus optical coherence tomography for quantifying retinal thickness

PURPOSE

To compare Cirrus Fourier-domain optical coherence tomography (OCT) with Stratus time-domain OCT for imaging retinal diseases and quantifying retinal thickness (RT) of all nine OCT zones, central macular thickness, and average macular thickness in eyes with and without macular edema.

DESIGN

Prospective comparison between two OCT systems.

METHODS

RT measurements were performed in 120 eyes of 60 patients suspected of having increased retina thickness using both Stratus and Cirrus OCT on the same day. Twenty-one eyes had both 512 x 128 and 200 x 200 Cirrus cube scans done.

RESULTS

Data from 101 eyes (53 patients) were analyzed; 46 eyes (45.5%) had macular edema on clinical examination (Group 1), whereas 55 eyes (54.4%) had no clinical evidence of macular edema (Group 2). There was modest correlation between all thickness measurements in 909 zones and each group (range of Pearson correlation, 0.51 to 0.89) and average value was significantly greater when measured with Cirrus OCT for all eyes (mean difference, 43.2 microm; P < .0001). There were few measurement differences between different resolution Cirrus cube scans.

CONCLUSIONS

Cirrus OCT measures RT approximately 43 microm greater than Stratus OCT, which is likely attributable to Cirrus OCT detection of the outer band of the retinal pigment epithelium vs Stratus OCT detection of the inner/outer segment photoreceptor junction. All zones showed a wide degree of variability in correlation. Both Cirrus cube scans provide similar data. Future studies comparing these systems might consider utilizing average macular thickness values, which reflect macular volume and may provide more consistent measurements.

Correlation between microaneurysms and retinal thickness in diabetic macular edema

PURPOSE

Microaneurysms commonly are believed to be related causally to retinal thickening in diabetic retinopathy, especially by leaking. The hypothesis that thicker areas of retina in diabetic retinopathy have more microaneurysms per unit area than areas that are not as thick was tested.

METHODS

Retinal thickness analysis was performed with a prototype instrument for 27 eyes of 27 diabetic patients and 22 normal eyes of 22 healthy subjects. Maps of retinal thickness were created, and microaneurysms were counted in zones having four levels of retinal thickness.

RESULTS

There was no increase in either total microaneurysms or apparent leaking microaneurysms per unit area with increasing levels of retinal thickness (P = 0.77 and 0.87, respectively).

CONCLUSION

Some microaneurysms may not cause thickening, or other factors may contribute to retinal thickening in diabetic retinopathy. The results may have implications on the pathogenesis of diabetic macular edema.

Screening for cystoid macular oedema in children with uveitis using the retinal thickness analyser

PURPOSE

This study aimed to investigate the retinal thickness analyser (RTA) as a means to identify the presence of cystoid macular oedema (CMO) in children with uveitis, whether the course of CMO can be monitored using this method, and whether there is a trend towards a correlation between macular oedema and visual acuity (VA) in children.

METHODS

This prospective, cross-sectional study with observer-blinded analysis included 25 eyes. Standardized testing for best corrected distance VA (d-VA), near (reading) VA (n-VA) and slit-lamp examination were conducted. Using the RTA, a 3 x 3-mm scan of the macula was obtained, which was then used to discern CMO and calculate mean foveal thickness (MFT).

RESULTS

Macular scanning was possible in all children. Cystoid macular oedema was discerned in 10 eyes (40%) and ruled out in 15. In CMO eyes, d-VA was 0.5 Snellen and n-VA was 2 Jaeger; neither result differed significantly from those in eyes without CMO. Mean foveal thickness correlated with n-VA (r = 0.511, p = 0.015), but not with d-VA (r = 0.271, p = 0.191). After 3 months of tailored therapy, CMO was still detectable in six eyes. Changes in d-VA in the CMO and non-CMO groups were 3 +/- 2.1 and 0.8 +/- 1.8 Snellen, respectively; changes in n-VA were 1 +/- 1.4 and 0.1 +/- 0.3 Jaeger, respectively. Changes in MFT were - 244.8 +/- 137.4 microm and - 0.8 +/- 18.1 microm, respectively. A statistically significant correlation was found between the changes in MFT and n-VA (r = 0.629), but not with that in d-VA (r = 0.292).

CONCLUSIONS

We used the RTA to establish the presence or absence of CMO according to measurements of the macular region. Our findings show that CMO is a common complication in children with uveitis and can be present even in cases with good d-VA. Mean foveal thickness as measured with the RTA correlates indirectly with n-VA.

Laser Scanning Imaging for Macular Disease

OBJECTIVE

To evaluate currently available data in the published literature to answer the question of whether laser scanning imaging is a sensitive and specific tool for detecting macular disease when compared with the current standard technique of slit-lamp biomicroscopy or stereoscopic fundus photography.

METHODS

Literature searches conducted in December 2004 and in August 2006 retrieved 370 citations. The Retina Panel members selected 65 articles for the panel methodologist to review and rate according to the strength of the evidence. Of the 65 articles reviewed, 6 provided level I evidence, 9 provided level II evidence, and 50 provided level III evidence. A level I rating was assigned to studies that reported an independent masked comparison of an appropriate spectrum of consecutive patients, all of whom had undergone both the diagnostic test and the reference standard. A level II rating was assigned to an independent masked or objective comparison; a study performed in a set of nonconsecutive patients or confined to a narrow spectrum of study individuals (or both), all of whom had undergone both the diagnostic test and the reference standard; or an independent masked comparison of an appropriate spectrum, but the reference standard had not been applied to all study patients. A level III rating was assigned when the reference standard was unobjective, unmasked, or not independent; positive and negative tests were verified using separate reference standards; or the study was performed in an inappropriate spectrum of patients.

RESULTS

There are high-level studies of the use of laser scanning imaging to quantify macular thickness and, thereby, macular edema in patients with diabetic retinopathy and to examine patients with a macular hole. There is lower-quality evidence on the use of laser scanning imaging for other diseases of the macula. There is insufficient evidence to compare the different instruments.

CONCLUSIONS

There is level I evidence that laser scanning imaging can accurately and reliably quantify macular thickness in patients with diabetic retinopathy. There is level I evidence that optical coherence tomography provides additional information to clinical examination when used in patients with a macular hole. Laser scanning imaging provides important information that is helpful in patient management by allowing objective serial quantitative measurements. Although further studies are needed to develop an optimal testing strategy using these imaging modalities, laser scanning imaging is a sensitive, specific, reproducible tool for diagnosing macular edema and, therefore, is likely to be useful for managing diseases that result in macular edema.

Laser Treatment in Diabetic Retinopathy

Diabetic retinopathy is a leading cause of visual impairment and blindness in developed countries due to macular edema and proliferative diabetic retinopathy (PDR). For both complications laser treatment may offer proven therapy: the Diabetic Retinopathy Study demonstrated that panretinal scatter photocoagulation reduces the risk of severe visual loss by >50% in eyes with high-risk characteristics. Panretinal scatter coagulation may also be beneficial in other PDR and severe nonproliferative diabetic retinopathy (NPDR) under certain conditions. For clinically significant macular edema the Early Treatment of Diabetic Retinopathy Study could show that immediate focal laser photocoagulation reduces the risk of moderate visual loss by at least 50%. When and how to perform laser treatment is described in detail, offering a proven treatment for many problems associated with diabetic retinopathy based on a high evidence level.

Topography of diabetic macular oedema compared with fluorescein angiography

PURPOSE

To compare the amount and pattern of fluorescein leakage in diabetic macular oedema with the retinal thickness maps obtained with the retinal thickness analyser (RTA) and optical coherence tomography (OCT).

METHODS

A consecutive series of 30 eyes from 30 patients with diabetic macular oedema was included. On fluorescein angiography (FA) the macula was analysed in 10 subfields as defined by the ETDRS. The amount and source of leakage for each field were determined. Retinal thickness was measured by OCT and RTA maps in each of the 10 fields and compared with the FA grading.

RESULTS

Foveal retinal thickness on OCT was most influenced by the overall FA leakage, which was the only significant covariate on multivariate analysis. The source and amount of leakage correlated significantly with the topography of retinal thickness in the four peripheral fields between 1500 microm and 3000 microm from the macular centre (r = 0.54, p = 0.002). The mean amount and source of leakage in those fields also showed the highest correlation with central macular thickness on OCT (r = 0.46, p = 0.01). Similar results were obtained by RTA when excluding ischaemic cases (r = 0.44, p = 0.04). For both instruments, FA leakage within the four central fields < 1500 microm did not correlate significantly with retinal thickness. Thickness by OCT and RTA were highly correlated with one another for central macular measurements (r = 0.73, p < 0.001), but correlated poorly in the peripheral fields. Overall, OCT measurements correlated more highly with FA.

CONCLUSIONS

Optical coherence tomography and RTA thickness measurements can be used to identify patients for further examination. Fluorescein angiography leakage in the outer ETDRS fields correlates best with central thickness and retinal thickness topography by OCT.

Prosthetic interfaces with the visual system: biological issues

The design of effective visual prostheses for the blind represents a challenge for biomedical engineers and neuroscientists. Significant progress has been made in the miniaturization and processing power of prosthesis electronics; however development lags in the design and construction of effective machine-brain interfaces with visual system neurons. This review summarizes what has been learned about stimulating neurons in the human and primate retina, lateral geniculate nucleus and visual cortex. Each level of the visual system presents unique challenges for neural interface design. Blind patients with the retinal degenerative disease retinitis pigmentosa (RP) are a common population in clinical trials of visual prostheses. The visual performance abilities of normals and RP patients are compared. To generate pattern vision in blind patients, the visual prosthetic interface must effectively stimulate the retinotopically organized neurons in the central visual field to elicit patterned visual percepts. The development of more biologically compatible methods of stimulating visual system neurons is critical to the development of finer spatial percepts. Prosthesis electrode arrays need to adapt to different optimal stimulus locations, stimulus patterns, and patient disease states.

Analysis of macular edema after cataract surgery in patients with diabetes using optical coherence tomography

OBJECTIVE

To assess the incidence or progression of macular edema (ME) after cataract surgery in diabetic patients using optical coherence tomography (OCT) and correlating this with degree of diabetic retinopathy or other risk factors.

DESIGN

Prospective cohort study.

PARTICIPANTS

Fifty diabetic eyes undergoing cataract surgery.

METHODS

Each eye underwent 7-field fundus photography no more than 3 months before surgery. Optical coherence tomography testing was performed within 4 weeks before surgery and at 1- and 3-month postoperative visits. Best-corrected visual acuity (BCVA) was recorded at each visit. Macular edema was defined as an increase of center point thickness on OCT > 30% from preoperative baseline.

MAIN OUTCOME MEASURES

Changes in foveal thickness and BCVA.

RESULTS

The incidence of ME on OCT was 22% (95% confidence interval, 13%-35%). The average increase in center point thickness at 1 month for eyes with ME was 202 microm, which resulted in a nearly 1-line loss of vision (0.07 logarithm of the minimum angle of resolution [logMAR] units) compared with eyes without ME gaining >2 lines of vision (0.24 logMAR units) (P>0.001). Eyes with no diabetic retinopathy developed minimal thickening of 18 mum and 14 mum at 1 and 3 months, respectively, associated with approximately 2 and 3 lines of improved vision, respectively (0.22 and 0.26 logMAR units). Eyes with moderate or severe nonproliferative diabetic retinopathy or proliferative diabetic retinopathy developed thickening of 145 mum and 131 mum at 1 and 3 months, respectively, associated with <1 and 2 lines of improved visual acuity, respectively (0.08 and 0.17 logMAR units). This difference (P = 0.05) in thickening (127 microm and 117 mum at 1 and 3 months, respectively) was correlated inversely with visual improvement (r = -0.662). Both duration of diabetes > or = 10 years (P = 0.04) and insulin dependence (P = 0.007) were associated with reduced visual improvement.

CONCLUSIONS

Diabetic eyes have a high incidence of increased center point thickness on OCT after cataract surgery, associated with a loss of vision at 1 month, with limited visual recovery at 3 months. Treatment to prevent this might improve outcomes in similar individuals after surgery.

Diabetic macular oedema: a clinical overview

Diabetic retinopathy is the leading cause of blindness in working aged-adults in westernised countries. Diabetic macular oedema (DMO) is a manifestation of diabetic retinopathy and is the leading cause of the visual impairment that occurs with diabetic retinopathy. There are multiple ways of classifying DMO; however, none appear to be wholly satisfactory. DMO occurs more frequently in type 2 diabetes mellitus, and appears to be more prevalent as the duration of diabetes increases, and as the severity of diabetic retinopathy worsens. There are multiple risk factors in common with diabetic retinopathy, such as hyperglycaemia, hypertension and dyslipidaemia; however, specific factors such as the presence of renal disease appear to be more significantly associated with DMO. Whereas the gold standard for diagnosis of DMO is via clinical examination, there is considerable variability involved, and hence, this has led to the advent of more objective methods of quantifying the degree of retinal thickness, such as optical coherence tomography. Laser photocoagulation appears to be the only universally acceptable treatment of choice to date; however, this is a destructive therapy, and its side effects coupled with the suboptimal efficacy has led to the advent of potential new therapies which will undoubtedly compliment the existing approaches, in the future management of a patient with DMO.

A reference standard for the measurement of macular oedema

Macular oedema is associated with several conditions that lead to blindness. Accurate measurement of macular thickness is important in order to follow disease progression and evaluate treatments. Four techniques are examined to determine the best reference standard for the detection and quantification of macular oedema: ultrasound, optical coherence tomography, the retinal thickness analyser, and the scanning laser ophthalmoscope. The three optical techniques have the highest resolution and sensitivity, in particular optical coherence tomography. Ultrasound can be useful where dense opacities preclude optical imaging.

Optical coherence tomography: a key to the future management of patients with diabetic macular oedema

Diabetic macular oedema is a major cause of visual loss in patients with diabetes. It usually results from the breakdown of the inner blood-retinal barrier. Early detection of retinal abnormalities is vital in preventing diabetic macular oedema and subsequent loss of vision, whilst assessment of retinal thickness is important for treatment and follow-up. Until recently, however, the methods available for detecting and evaluating diabetic macular oedema were slit-lamp biomicroscopy and stereoscopic photography, both of which are limited in detecting earlier retinal changes. Optical coherence tomography (OCT) is a new diagnostic imaging modality that provides high-resolution, cross-sectional images of the eye. It is proving to be an accurate tool for the early diagnosis, analysis and monitoring of retinopathy, with high repeatability and resolution. It allows not only the qualitative diagnosis of diabetic macular oedema, but also the quantitative assessment of oedema. This article reviews the future role of OCT in the management of patients with diabetic macular oedema.

Test-retest variability in structural and functional parameters of glaucoma damage in the glaucoma imaging longitudinal study

PURPOSE

To determine the test-retest variability in perimetric, optic disc, and macular thickness parameters in a cohort of treated patients with established glaucoma.

PATIENTS AND METHODS

In this cohort study, the authors analyzed the imaging studies and visual field tests at the baseline and 6-month visits of 162 eyes of 162 participant in the Glaucoma Imaging Longitudinal Study (GILS). They assessed the difference, expressed as the standard error of measurement, of Humphrey field analyzer II (HFA) Swedish Interactive Threshold Algorithm fast, Heidelberg retinal tomograph (HRT) II, and retinal thickness analyzer (RTA) parameters between the two visits and assumed that this difference was due to measurement variability, not pathologic change. A statistically significant change was defined as twice the standard error of measurement.

RESULTS

In this cohort of treated glaucoma patients, it was found that statistically significant changes were 3.2 dB for mean deviation (MD), 2.2 for pattern standard deviation (PSD), 0.12 for cup shape measure, 0.26 mm for rim area, and 32.8 microm and 31.8 microm for superior and inferior macular thickness, respectively. On the basis of these values, it was estimated that the number of potential progression events detectable in this cohort by the parameters of MD, PSD, cup shape measure, rim area, superior macular thickness, and inferior macular thickness was 7.5, 6.0, 2.3, 5.7, 3.1, and 3.4, respectively.

CONCLUSIONS

The variability of the measurements of MD, PSD, and rim area, relative to the range of possible values, is less than the variability of cup shape measure or macular thickness measurements. Therefore, the former measurements may be more useful global measurements for assessing progressive glaucoma damage.

Refraction and aberration across the horizontal central 10 degrees of the visual field

PURPOSE

The purpose of this study was to measure refraction and aberrations across the horizontal central visual field.

METHODS

Cycloplegic refraction was measured on eight subjects at 13 points across the horizontal central 10 degrees of the retina using a Hartmann-Shack wavefront sensor. Refractions were converted into mean sphere (M), 90 degrees to 180 degrees astigmatism (J180), and 45 degrees to 135 degrees astigmatism (J45) components. For five subjects, higher-order aberrations were determined at the center and edges of the field.

RESULTS

Subtle changes in refraction were found to exist across the central 10 degrees of the retina, with changes in mean best sphere varying by up to half a diopter across this region and with smaller changes in astigmatism. Horizontal coma, but no other higher-order aberrations, varied systemically across the visual field; it varied linearly with angle but at different rates for the different subjects.

CONCLUSION

Subtle changes in cycloplegic refraction exist across the horizontal central 10 degrees of the retina. The results indicate the need for correct alignment when measuring objective refraction.

Posterior pole retinal thickness measurements by the retinal thickness analyzer in healthy Chinese subjects

PURPOSE

To assess retinal thickness at the posterior pole in healthy Chinese subjects with the retinal thickness analyzer (RTA).

METHODS

Retinal thicknesses at the posterior pole and fovea were measured by the RTA in 331 eyes of 178 healthy Chinese subjects. Retinal thicknesses as a function of sex, age, refractive errors, and axial length were also evaluated.

RESULTS

The average thickness of the foveal area +/- SD was 158.6 +/- 24.8 microm, the average thickness of the perifoveal region (600-2,500 microm from fovea) +/- SD was 174 +/- 25.2 microm, and the average thickness of the posterior pole region (600-6,000 microm from fovea) +/- SD was 171.9 +/- 25.3 microm. There was no significant difference in retinal thicknesses of the foveal, perifoveal, and posterior pole regions in either right or left eyes or as a function of different spherical equivalents. Moreover, there was no significant difference of foveal thickness between males and females. Greater retinal thicknesses of the foveal, perifoveal, and posterior pole regions were associated with age of older than 40 years and axial length of < 24 mm, and greater perifoveal and posterior pole thicknesses were found for females. Furthermore, there were no significant correlations between age, refractive errors, and axial lengths with retinal thicknesses.

CONCLUSION

Retinal thicknesses of the posterior pole region differed by age, axial length, and sex, but there was no effect of laterality or different spherical equivalents. The RTA is a fast and noninvasive technology to assess retinal conditions with thickening or thinning in the fovea and posterior pole.

Diagnostic accuracy of the Retinal Thickness Analyser: differentiation between normal eyes and eyes with glaucoma or macular pathologies

BACKGROUND

The Retinal Thickness Analyser (RTA) is intended to detect glaucomatous changes as well as macular pathologies at the posterior pole. We determined the diagnostic accuracy for eyes with manifest glaucoma or macular diseases.

METHODS

We examined 71 eyes with long-term, established eye conditions. Included were 28 eyes with glaucoma, 21 with different macular diseases and 22 normal eyes. All examinations were evaluated in a blind-test by RTA experts without any clinical information on the patients. After comparison of the RTA interpretation with the clinical diagnosis, we determined sensitivity, specificity, positive and negative predictive values.

RESULTS

Of 71 examinations, 15 (21%) were not interpretable. If these results are excluded, the following diagnostic accuracy values were calculated for glaucoma and macular disorders respectively: sensitivity 75 and 59%, specificity 55 and 97%, positive predictive value 48 and 90% and negative predictive value 80 and 84%. These values were not significantly different when both eyes of each patient were included in the final analysis (n=133).

CONCLUSION

The diagnostic values of the RTA determined in this case control study were not satisfactory. However, no clinical information was used in the assessment. The extent to which additional clinical information increases the diagnostic value remains to be determined.

Retinal thickness in diabetic retinopathy: comparison of optical coherence tomography, the retinal thickness analyzer, and fundus photography

BACKGROUND

Optical coherence tomography (OCT) and the retinal thickness analyzer (RTA) have proved their ability to measure retinal thickness in healthy subjects and diabetics reliably. In the present study, both techniques were compared for the same study population of diabetic patients, and the findings were related to macular edema shown by stereo fundus photography (SFP).

METHODS

Maculas of 124 eyes from 69 patients with diabetes mellitus were examined with OCT and the RTA. Measurements of retinal thickness were compared with signs of macular edema shown by SFP. For each eye, nine different sectors were analyzed (a foveal sector, four parafoveal sectors, and four extrafoveal sectors). Thirteen eyes with a normal macula served as controls. Sensitivity and specificity of detecting clinically significant macular edema (CSME) were calculated.

RESULTS

Of 111 eyes, 64 showed signs of CSME by SFP. Mean retinal thickness +/- SD of the foveal sector was 249 +/- 104 microm by RTA and 295 +/- 124 microm by OCT measurements. There was a moderate overall correlation between OCT and the RTA (r = 0.66). The correlation was best in the foveal sector (r = 0.82). Overall correlation with SFP was better for OCT (r = 0.77) than for the RTA (r = 0.62). Sensitivity of detecting CSME was consistently higher with OCT, while the RTA showed higher specificity.

CONCLUSION

Both measuring techniques yielded similar results when examining eyes of patients with diabetes, although absolute values differed. OCT seems to be more suitable in the clinical screening for macular edema due to its high sensitivity (>90%) with appropriate analysis parameters. The RTA is more prone to erroneous or missing thickness readings particularly under difficult measuring conditions.

Normal macular thickness measurements in healthy eyes using Stratus optical coherence tomography

OBJECTIVE

To report normal macular thickness measurements in healthy eyes using the latest commercially available optical coherence tomography (OCT) mapping software, version 3.0, from the Stratus OCT (OCT3).

METHODS

Thirty-seven eyes from 37 healthy subjects underwent a complete ophthalmologic examination, including OCT. Six radial scans, 6 mm in length and centered on the fovea, were obtained using the OCT3. Retinal thickness was automatically calculated by OCT mapping software. Measurements were displayed as the mean and standard deviation for each of the 9 regions defined in the Early Treatment Diabetic Retinopathy Study.

RESULTS

Foveal thickness (mean thickness in the central 1000-microm diameter area) and central foveal thickness (mean thickness at the point of intersection of 6 radial scans) on the OCT3 were 212 +/- 20 and 182 +/- 23 microm, respectively. Macular thickness measurements were thinnest at the center of the fovea, thickest within 3-mm diameter of the center, and diminished toward the periphery of the macula. The temporal quadrant was thinner than the nasal quadrant. Central foveal thickness was also manually determined as 170 +/- 18 microm, approximately 12 microm less than the value automatically obtained from the OCT3 software. There was no correlation between age and foveal thickness (P = .80).

CONCLUSIONS

Mean foveal thickness measurements were 38 to 62 microm thicker than previously reported values, while mean central foveal thickness measurements were 20 to 49 microm thicker than previously published values. This discrepancy should be considered when interpreting OCT scans.

Posterior pole retinal thickness in ocular hypertension and glaucoma: early changes detected by hemispheric asymmetries

PURPOSE

To evaluate retinal thickness at the posterior pole of the fundus in ocular hypertension (OHT) and open-angle glaucoma (OAG), and to correlate morphometric findings with visual sensitivity as determined by automated perimetry.

METHODS

One randomly selected eye from 41 patients with clinical diagnosis of OHT (n = 25) or early to moderate OAG (n = 16) and 16 age-matched normal controls was examined. Retinal thickness was measured by Retinal Thickness Analyzer (RTA), acquiring 5 pre-defined scans covering the central 20 degrees of the fundus. RTA average thickness and thickness profile data, including hemispheric asymmetries calculated as relative (superior/inferior and nasal/temporal) or absolute (vertical and horizontal, ie, independent of which hemisphere was thinner) parameters, were calculated. For each eye, white-on-white Humphrey 30-2 visual field results were analyzed, in addition to standard global indices, by quantifying perimetric sensitivities for regions of the posterior pole corresponding to those sampled by the RTA.

RESULTS

On average, central retinal thickness was reduced (P < 0.05) in OAG compared with OHT or normal control eyes. Vertical hemispheric absolute thickness asymmetry was increased (P < or = 0.01) in OAG eyes compared with the other groups. Horizontal hemispheric absolute thickness asymmetry was increased (P < 0.01) in both OHT and OAG eyes, compared with control eyes. At least one of the RTA parameters was altered in 13 of 25 OHT (52%) and 12 of 16 OAG eyes (75%), most frequently involving thickness asymmetries. In OAG, but not OHT eyes, superior/inferior asymmetry was positively (r = 0.69, P < 0.01) correlated with the corresponding asymmetry in perimetric sensitivity.

CONCLUSIONS

The RTA can reveal increased hemispheric thickness asymmetries in both OHT and OAG eyes. In OAG eyes thickness asymmetries are associated with corresponding perimetric asymmetries. The findings in OHT eyes suggest that localized anatomic and functional damage to inner retina may not develop in parallel early in the disease process.

Age Effect on Retina and Optic Disc Normal Values

PURPOSE

To investigate retinal thickness and optic disc parameters by the Retinal Thickness Analyzer (RTA) glaucoma program in older normal subjects and to determine any age effect.

METHODS

Subjects over 40 years of age without any prior history of eye diseases were recruited. Only subjects completely normal on clinical ophthalmologic examination and on visual field testing by Humphrey Field Analyzer (HFA) using the SITA 24-2 program were included. A total of 74 eyes from 74 subjects with even age distribution over the decades were enrolled and underwent topographic measurements of the posterior pole and of the optic disc by RTA. The 'glaucoma full' program in software version 4.11B was applied.

RESULTS

Mean patient age was 59.9 +/- 10.3 years with a range from 40 to 80 years. The only parameter intraocular pressure (IOP) correlated with was retinal posterior pole asymmetry (r = 0.27, p = 0.02). IOP itself increased significantly with age (r = 0.341, p = 0.003). Mean defect and pattern standard deviation of the HFA did not correlate with any of the retinal or optic disc measurements. Increasing age correlated significantly with some of the morphologic measurements of the RTA: decreasing perifoveal minimum thickness (r = -0.258, p = 0.026), increased cup-to-disc area ratio (r = 0.302, p = 0.016) and increased cup area (r = 0.338 p = 0.007).

CONCLUSIONS

An age effect exists for some of the retina and optic disc measurements obtained by the RTA.

Mapping of the retinal pigment epithelium in exudative age related macular degeneration

PURPOSE

To evaluate a novel technique for three-dimensional mapping of the retinal pigment epithelium (RPE) layer in patients with subfoveal choroidal neovascularization (CNV) due to age-related macular degeneration.

METHODS

Scanning with a recent generation retinal thickness analyzer (RTA) was performed in consecutive patients undergoing fluorescein angiography. From a 3 x 3 mm area centered on the fovea, three-dimensional area maps of the RPE level were calculated by external spreadsheet software. Included were 18 eyes with classic CNV, 18 eyes with occult CNV and 18 eyes from age-matched normal subjects. Repeatability was assessed by measuring 17 eyes with CNV 3 times. In ten additional patients, RTA imaging results were compared with cross-sections obtained by optical coherence tomography.

RESULTS

By both methods, distinctive changes in RPE level maps were observed in classic and occult CNV. In classic CNV with the lesion extending over the RPE, only focal irregularities in the anteriorly displaced RPE surface were observed. In contrast, mapping of occult CNV showed a more irregular displacement of the RPE layer. The RPE map standard deviation indicating surface irregularity differed statistically significantly between the groups, with coefficients of variance of 5.9% for controls, 6.1% for classic and 8.8% for occult CNV (P < 0.001). Regarding repeatability, RPE level maps showed 1.2% coefficient of variance and an intra-class correlation coefficient of 0.87 for triplicate measurements in CNV patients.

CONCLUSIONS

Topographic mapping of CNV lesions offers a fast, reproducible method for obtaining three-dimensional morphometric information on the RPE level and to quantify changes.

OPTICAL COHERENCE TOMOGRAPHY IN UNILATERAL RESOLVED CENTRAL SEROUS CHORIORETINOPATHY

PURPOSE

To evaluate the correlation between optical coherence tomographic evaluations of foveal thickness and anatomical changes within the fovea and visual acuity in patients who have unilateral resolved central serous chorioretinopathy.

METHODS

A retrospective review of cases of unilateral resolved central serous chorioretinopathy imaged with high-resolution optical coherence tomography was performed. The foveal thickness of the involved eye was normalized by dividing its thickness by that of the uninvolved fellow eye. The best-corrected visual acuity of the involved eye was normalized as well. The normalized foveal thickness was compared with the normalized visual acuity. The anatomical findings of the fovea were compared with the visual acuity.

RESULTS

Twenty patients were evaluated (11 men and 9 women; age range, 31-66 years [mean, 46.8 years]). The mean foveal thickness was 135.8 mum in the involved eyes and 184.4 mum in the uninvolved eyes (P < 0.001). There was a correlation between the normalized foveal thickness and the normalized visual acuity (Spearman rho, 0.67; P = 0.001). The external limiting membrane was visible in 7 (35%) of the involved eyes compared with 19 uninvolved eyes (95%) (P < 0.001). In the involved eyes, those with a visible external limiting membrane had better visual acuity than did those that did not (P = 0.001). It was possible to visualize the boundary between the photoreceptor cell bodies and the outer segments in 8 (40%) of the involved eyes and in the 17 uninvolved eyes (85%) (P < 0.001). In the involved eyes, those with a visible boundary between the photoreceptor bodies and the outer segments had a better visual acuity than did those that did not (P = 0.019).

CONCLUSIONS

Patients with unilateral resolved central serous chorioretinopathy had a decrease in the central foveal thickness in the involved eyes, and there was a statistically significant correlation between the foveal thickness and the visual acuity, even in eyes with relatively good visual acuity. The inability to observe a discrete signal corresponding to the external limiting membrane layer was more common in involved eyes and was significantly associated with decreased visual acuity. This same relationship was seen with the ability to visualize the boundary between the photoreceptor bodies and the outer segments; this boundary was less commonly observed in involved eyes and was associated with decreased visual acuity. Resolved central serous chorioretinopathy causes a number of morphologic changes in the fovea that are associated with visual acuity.

[Reproducibility of measurements of the peripapillary retinal nerve fibre layer thickness. Optical coherence tomography versus retinal thickness analyzer]

PURPOSE

The aim of this study was to compare the intra- and inter-examiner reproducibility of measurements obtained by optical coherence tomography (OCT) and retinal thickness analyzer (RTA).

PATIENTS AND METHODS

During a period of 2 months, 22 eyes of 16 patients and 6 healthy subjects were included. Two examiners (EMH, RK) successively performed three measurements of the peripapillary retinal nerve fibre layer (RNFL) thickness with RTA and OCT. The reproducibility of three individual measurements of one examiner (intra-examiner) as well as the reproducibility of the measurements between both examiners (inter-examiner) was evaluated using the Friedman test and sign test.

RESULTS

The average thickness of the peripapillary RNFL was 154.4 microm for the first investigator (EMH) and 155.1 microm for the other investigator (RK) measured with RTA. The results obtained by OCT were 137.3 microm (EMH) and 138.9 microm (RK), respectively, generally indicating a threefold smaller range. Comparing the three measurements of one single examiner, no appreciable intra-observer dependency neither for RTA (EMH: p=0.19, RK: p=0.95) nor for OCT (EMH: p=0.51, RK: p=0.62) was observed. Inter-examiner analysis for RTA and OCT also revealed an acceptable reproducibility.

CONCLUSIONS

Measurements of peripapillary RNFL thickness using RTA and OCT exhibited intra- and inter-observer agreement.

OPTICAL COHERENCE TOMOGRAPHY OF CHOROIDAL NEVUS IN 120 PATIENTS

OBJECTIVE

To describe the optical coherence tomography (OCT) findings of choroidal nevi.

METHODS

Retrospective, single-center case series of 120 eyes of 120 consecutive patients with choroidal nevi who were evaluated by OCT. Diagnostic imaging was performed with a Zeiss StratusOCT Model 3000 (Carl Zeiss Ophthalmic Systems, Dublin, CA) using scan acquisition protocols of 6 radial lines and retinal thickness analysis overlying the nevus.

RESULTS

The mean patient age was 59 years (median, 60 years; range, 14-87 years). The choroidal nevus was a mean of 5.2 mm in basal dimension and 1.7 mm in thickness and was located a mean of 2.7 mm from the optic disk and 2.5 mm from the foveola. Related retinal findings by ophthalmoscopic evaluation included overlying retina edema (3%), subretinal fluid (16%), retinal thinning (0%), drusen (58%), and retinal pigment epithelium (RPE) detachment (2%). In comparison, related retinal findings at the site of the nevus by OCT included overlying retina edema (15%), subretinal fluid (26%), retinal thinning (22%), drusen (41%), and RPE detachment (12%). Furthermore, OCT permitted classification of the overlying retinal edema as focal cystoid (3%), diffuse cystoid (8%), coalescent cystoid (3%), and noncystoid edema (1%). By OCT, the overlying retina was normal thickness (32%), thinned (22%), or thickened (45%), and photoreceptor loss or attenuation was noted in 51% of cases. Specific OCT findings of the choroidal nevus were limited to its anterior surface with minimal penetration into the mass. These findings included increased thickness of the RPE/choriocapillaris layer (68%) and optical qualities within the anterior portion of the nevus of hyporeflectivity (62%), isoreflectivity (29%), and hyperreflectivity (9%). Hyporeflectivity was observed in 68% of pigmented nevi and 18% of nonpigmented nevi. When comparing OCT with clinical examination, OCT was more sensitive in the detection of related retinal edema, subretinal fluid, retinal thinning, photoreceptor attenuation, and RPE detachment.

CONCLUSIONS

OCT is a useful diagnostic modality for imaging the retina overlying a choroidal nevus. Numerous overlying changes such as subretinal fluid, retinal edema, retinal thinning, and photoreceptor attenuation are visible by OCT.

Screening der diabetischen Retinopathie und Papillentopographie mit dem ?Retinal Thickness Analyzer? (RTA)

BACKGROUND

The RTA features a fundus photography mode and optic disc topography. Those two new modes were investigated regarding their clinical use.

METHODS

First, the combination of wide-field photography with a retinal thickness map was assessed for tele-screening for diabetic retinopathy in 31 eyes. Second, normal values of the optic disc were collected on 30 non-glaucomatous probands in the non-mydriatic mode and compared to the results of the mydriatic mode, for which reproducibility was also investigated.

RESULTS

For diabetic retinopathy, the RTA yielded mean 93% sensitivity for proliferative diabetic retinopathy and 100% sensitivity for detecting diabetic macular edema compared to clinical examination at specificities ranging from 58 to 96%. Regarding the measurements of the optic disc, the normal values in mydriasis coincided with those in miosis in all but 4 of 12 parameters.

CONCLUSIONS

The RTA is suitable for application in tele-screening for diabetic retinopathy. The topography of the optic disc is highly reproducible and may be used for glaucoma diagnostics.

[Optical coherence tomography for macular edema. Classification, quantitative assessment, and rational usage in the clinical practice]

Optical coherence tomography (OCT) allows for morphological assessment of macular edema of various origins by producing two-dimensional images of the retina. In addition, retinal thickness can be measured quantitatively. In diabetic maculopathy, damage of the blood-retinal barrier can be indirectly assessed by locating the intraretinal fluid accumulation and the progress of maculopathy from diffuse to cystoid edema and even rupture of the retinal structure can be described as well as the formation of neurosensory retinal detachment with subretinal fluid. Increase of retinal thickness correlates with decrease in visual acuity. Detailed interpretation of OCT images can replace fluorescein angiography in certain cases, as has been shown for uveitis. In order to obtain correct classification of macular disease in routine clinical use, all images have to be completely assessed and compared to previous investigations and to the measurements of the fellow eye. More accurate normal values of retinal thickness and volume can be expected in the future. The importance of OCT in routine clinical assessment of macular edema will most probably continue to grow.

Optical coherence tomography in children: analysis of 44 eyes with intraocular tumors and simulating conditions

PURPOSE

To investigate the role of optical coherence tomography (OCT) in the evaluation of fundus tumors and simulating lesions in children.

PATIENTS AND METHODS

We report the results of a retrospective single-center case series of 44 eyes of 44 children younger than age 18 with fundus lesions who were evaluated with OCT. In comparison, 12 eyes of 12 children with a normal macula were evaluated with OCT. Main outcome measures were cooperation of children while undergoing OCT and correlation of OCT findings with clinical and ultrasonographic findings

RESULTS

The OCT was performed without difficulty in all 56 children. Mean patient age was 12 years (median, 12 years; range, 4 to 17 years). The mean horizontal foveal thickness in the 12 normal eyes was 137 microm (median, 132 microm; range, 109 to 185 microm). Clinical diagnoses included retinoblastoma in 10 (23%) eyes, Coats' disease in 4 (9%) eyes, retinal capillary hemangioma in 3 (7%) eyes, astrocytic hamartoma of the retina in 3 (7%) eyes, toxocara granuloma in 2 (5%) eyes, and others. OCT was more sensitive than clinical examination in detection of macular pathology including shallow posterior vitreous detachment, surface wrinkling maculopathy, cystoid and noncystoid macular edema, subfoveal fluid, and retinal thinning. In comparison to ultrasonography, OCT was more sensitive in detection of surface wrinkling maculopathy, macular edema, and subfoveal fluid. Ultrasonography was more sensitive in detection of posterior vitreous detachment.

CONCLUSIONS

OCT is a useful and well-tolerated diagnostic modality for macular evaluation in children. It is more sensitive than clinical examination and ultrasonography in the detection of surface wrinkling maculopathy, macular edema, and subfoveal fluid.

Relationship of Gender, Body Mass Index, and Axial Length with Central Retinal Thickness Using Optical Coherence Tomography

BACKGROUND

Optical coherence tomography (OCT) acquires cross-sectional retinal images with high resolution using low-coherence interferometry. Few studies have studied the effect of demographic data and ocular parameters that may affect central retinal thickness. In this study, these factors were used as parameters to analyse if any significant relationship exists with central retinal thickness.

METHODS

Volunteers with a best-corrected visual acuity of 6/12 or better and no evidence of ocular abnormalities or interventions were recruited from October 2001 to March 2003. Body mass index (BMI), autorefraction, and keratometry recordings were measured, followed by applanation tonometry and A-scan ultrasonography. The central retinal thickness of the right eye was analysed using a scan length of 3 cm. Another 25 eyes were selected for interobserver reproducibility.

RESULTS

In all, 117 normal subjects (60 male and 57 female subjects) were recruited. The mean thickness of the central retina with a diameter of 1 mm was 203+/-23 microm for male and 189+/-20 microm for female subjects. Age, intraocular pressure, and keratometric readings were not significantly correlated with central retinal thickness. Using multiple regression, gender, BMI, axial length, and signal-to-noise ratio (P<0.05) were significantly associated with the central retinal thickness. The intraclass correlation coefficient was 0.98 for interobserver reproducibility.

CONCLUSION

OCT has a high interobserver reproducibility. The male gender, larger BMI, and longer axial length are associated with a significantly thicker central retina and these parameters should be considered for assessing retinal thickening and baseline comparisons in future studies.

Imaging in glaucoma

Structural assessment using the imaging technologies discussed herein provides reproducible quantitative measurements of posterior segment ocular structures. These measurements have been found to provide useful data for glaucoma detection in various regions of the posterior segment. Further studies are needed to evaluate the utility of these technologies for pre-perimetric glaucoma detection and for monitoring glaucoma progression over an extended period.

Detection of laser in situ keratomileusis in a postmortem eye using optical coherence tomography

With more individuals having laser in situ keratomileusis (LASIK), eye banks are challenged to detect prior refractive surgery in donor tissue. We report the case of a donor who had LASIK 9 months before his death. Slitlamp biomicroscopy, corneal topography, and optical coherence tomography (OCT) were performed to evaluate the corneas. Few changes were detected under slitlamp examination and corneal topography. We demonstrate that OCT is capable of detecting LASIK-induced structural changes in the immediate postmortem evaluation and during the early and late period of organ culture. We recommend OCT screening of potential donor corneas before organ culture and between days 9 and 12 of organ culture.