Correlation among retinal thickness, optic disc, and visual field in glaucoma patients and suspects: a pilot study

Long-term risk factors for poor visual outcomes in patients with epiretinal membrane and open-angle glaucoma: a retrospective study

We aimed to identify prognostic risk factors for visual deterioration in eyes with epiretinal membrane (ERM) and open-angle glaucoma (OAG) through long-term follow-up. In this retrospective observational case series, we examined consecutive eyes with ERM and OAG over a minimum follow-up of 2 years. Visual outcomes and prognostic factors were analyzed in patients' eyes undergoing ERM peeling with pars plana vitrectomy (PPV) (peeling group) and only observation (observation group). Eyes followed for less than 2 years after PPV were excluded. Among 100 eyes from 84 patients, 31 and 69 eyes were classified into peeling and observation groups, respectively. Over the follow-up period, best-corrected visual acuity (BCVA) in the observation group worsened from 0.03 ± 0.19 to 0.14 ± 0.33 (P = 0.0003), whereas that in the peeling group remained stable. Multivariate analysis revealed microcystic macular edema (MME) (odds ratio: 4.97; 95% confidence interval [CI]: 1.52 to 16.2; P = 0.008) and thin central foveal thickness (CFT) (odds ratio: 0.99; 95% CI: 0.98 to 1.00; P = 0.033) as risk factors for visual acuity decay. The presence of MME and thin CFT were risk factors for long-term visual deterioration in eyes with ERM and concomitant OAG. Vitrectomy with ERM peeling for eyes with OAG may be considered to preserve BCVA.

Protective Effects of Pituitary Adenylate-Cyclase-Activating Polypeptide on Retinal Vasculature and Molecular Responses in a Rat Model of Moderate Glaucoma

Despite the high probability of glaucoma-related blindness, its cause is not fully understood and there is no efficient therapeutic strategy for neuroprotection. Vascular factors have been suggested to play an important role in glaucoma development and progression. Previously, we have proven the neuroprotective effects of pituitary adenylate-cyclase-activating polypeptide (PACAP) eye drops in an inducible, microbeads model in rats that is able to reproduce many clinically relevant features of human glaucoma. In the present study, we examined the potential protective effects of PACAP1-38 on the retinal vasculature and the molecular changes in hypoxia. Ocular hypertension was induced by injection of microbeads into the anterior chamber, while control rats received PBS. PACAP dissolved in vehicle (1 µg/drop) or vehicle treatment was started one day after the injections for four weeks three times a day. Retinal degeneration was assessed with optical coherence tomography (OCT), and vascular and molecular changes were assessed by immunofluorescence labeling. HIF1-α and VEGF-A protein levels were measured by Western blot. OCT images proved severe retinal degeneration in the glaucomatous group, while PACAP1-38 eye drops had a retinoprotective effect. Vascular parameters were deteriorated and molecular analysis suggested hypoxic conditions in glaucoma. PACAP treatment exerted a positive effect against these alterations. In summary, PACAP could prevent the severe damage to the retina and its vasculature induced by ocular hypertension in a microbeads model.

Optical Coherence Tomography Evaluation of Peripapillary and Macular Structure Changes in Pre-perimetric Glaucoma, Early Perimetric Glaucoma, and Ocular Hypertension: A Systematic Review and Meta-Analysis

Background: This study aimed to assess the differences in the average and sectoral peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell plus inner plexiform layer (mGCIPL), and macular ganglion cell complex (mGCC) thickness using optical coherence tomography (OCT) in patients with pre-perimetric glaucoma (PPG) compared to those with early perimetric glaucoma (EG) and ocular hypertension (OHT).

Methods: A comprehensive literature search of the PubMed database, the Cochrane Library, and Embase was performed from inception to March 2021. The weighted mean difference (WMD) with the 95% confidence interval (CI) was pooled for continuous outcomes.

Results: Twenty-three cross-sectional studies comprising 2,574 eyes (1,101 PPG eyes, 1,233 EG eyes, and 240 OHT eyes) were included in the systematic review and meta-analysis. The pooled results demonstrated that the average pRNFL (WMD = 8.22, 95% CI = 6.32–10.12, P < 0.00001), mGCIPL (WMD = 4.83, 95% CI = 3.43–6.23, P < 0.00001), and mGCC (WMD = 7.19, 95% CI = 4.52–9.85, P < 0.00001) were significantly thinner in patients with EG than in those with PPG. The sectoral thickness of pRNFL, mGCIPL, and mGCC were also significantly lower in the EG eyes. In addition, the average pRNFL and mGCC were significantly thinner in the PPG eyes than those in the OHT eyes (pRNFL: WMD = −8.57, 95% CI = −9.88 to −7.27, P < 0.00001; mGCC: WMD = −3.23, 95% CI = −6.03 to −0.44, P = 0.02). Similarly, the sectoral pRNFL and mGCC were also significantly thinner in the PPG eyes than those in the OHT eyes.

Conclusion: OCT-based measurements of peripapillary and macular structural alterations can be used to distinguish PPG from EG and OHT, which can help understand the pathophysiology of glaucoma at earlier stages. Studies that employ clock hour classification methods and longitudinal studies are needed to verify our findings.

Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=239798 CRD42021239798

Evaluation of the retinal nerve fiber layer and ganglion cell complex thicknesses in patients with exfoliation syndrome

Background/aim

This study aimed to evaluate retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thicknesses using spectral domain optical coherence tomography (SD-OCT) in both unilateral and bilateral exfoliation syndrome (XFS) patients

Materials and methods

Twenty-four patients with unilateral XFS, 20 patients with bilateral XFS, and 23 healthy subjects were enrolled in this study. Eyes with XFS were compared with both fellow eyes and age-matched control subject eyes in terms of mean and segmental RNFL thickness and minimum, mean, and segmental GCC thickness.

Results

In the bilateral XFS group, minimum GCC of the right eye (75.80 ± 11.6 μm) was significantly thinner compared with the right eyes of the control group (81.83 ± 6.6 μm) (P < 0.05). Also, superior RNFL was thinner in the right eye (106.90 ± 16.7 μm) compared with left eye (114.15 ± 18.1 μm) in the bilateral XFS group (P < 0.05). No significant differences in the unilateral XFS group were detected in GCC and RNFL analysis.

Conclusion

Minimum GCC value may be the first parameter affected in the conversion of XFS to exfoliative glaucoma followed by RNFL changes.

Diagnostic accuracy of posterior pole asymmetry analysis parameters of spectralis optical coherence tomography in detecting early unilateral glaucoma

Purpose:

To report the diagnostic ability of posterior pole asymmetry analysis (PPAA) parameters of spectralis optical coherence tomography (OCT) in detecting early unilateral glaucoma.

Methods:

A prospective, cross-sectional study which included 80 eyes of 80 normal subjects and 76 eyes of 76 patients with unilateral early primary open-angle glaucoma by Hodapp-Anderson-Parrish classification. All subjects were of age more than 18 years, best-corrected visual acuity 20/40 or better, and a refractive error within ± 5 diopter (D) sphere and ± 3 D cylinder. Control subjects had a normal ocular examination, intraocular pressure (IOP) <22 mmHg, no past history of high IOP, no family history of glaucoma, normal optic disc morphology, and visual field in both eyes. One eye of the control subject was randomly included. All eyes underwent OCT for retinal nerve fiber layer (RNFL) analysis and PPAA. The number of continuous black squares was noted in the asymmetry analysis (right-left + hemisphere asymmetry). The area under curve (AUC) was calculated for all OCT parameters.

Results:

The best value for AUC for RNFL analysis was 0.858 for the inferotemporal quadrant thickness. This was similar to the best value for AUC for PPAA which was 0.833 for the inferior macular thickness parameter (P = 0.5). The AUC for the right-left and the hemisphere asymmetry part of PPAA was 0.427 and 0.499, respectively.

Conclusion:

The macular thickness PPAA parameters were equally good as the RNFL parameters. However, the asymmetry analysis parameters performed poorly and need further refinement before its use in early unilateral glaucoma diagnosis.

Identification of the Most Accurate Spectral-domain Optical Coherence Tomography Parameters in Eyes With Early High-Tension and Low-Tension Glaucoma

PURPOSE

The aim of the study was to compare the diagnostic ability of macular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (pRNFL) thickness in high-tension glaucoma (HTG) and low-tension glaucoma (LTG).

PATIENTS AND METHODS

Glaucoma was defined as glaucomatous optic neuropathy and reproducible visual field defects. Patients were classified as having LTG if untreated intraocular pressure was ≤21 mm Hg on 2 different occasions. Only eyes with early glaucoma (mean deviation <-6 dB) were included. All patients underwent spectral-domain optical coherence tomography (SDOCT) imaging.

RESULTS

A total of 56 normal subjects, 64 HTG patients, and 35 LTG patients were enrolled. Overall, after adjusting for mean deviation and age, the average pRNFL thickness in eyes with LTG was 18.7 µm thinner than in eyes with HTG (17% difference, P<0.01). In the HTG group, no significant difference was found between areas under the receiver operating characteristic curve (AUCs) for average GCC and average pRNFL thicknesses (0.77 vs. 0.68, P=0.06). In the LTG group, average pRNFL thickness had a significantly larger AUC compared with average GCC thickness (0.95 vs. 0.81, P<0.001). Comparing AUCs between HTG and LTG groups, although the average GCC had similar AUCs in both groups (P=0.47), the average pRNFL thickness had a significantly larger AUC in the LTG group (P<0.001).

CONCLUSIONS

In eyes with early glaucoma, the pRNFL thickness scan seems to be a more accurate SDOCT protocol to identify those with LTG compared with the GCC thickness scan.

Microcystic Macular Changes in Primary Open-angle Glaucoma

PURPOSE

To describe microcystic macular changes in patients with moderate to advanced primary open-angle glaucoma.

PATIENTS AND METHODS

Eleven eyes of 6 unrelated patients were retrospectively identified based on a disproportionately preserved macular thickness on optical coherence tomography (OCT) despite severe peripapillary retinal nerve fiber layer thinning. Patient demographic, history, and examination findings were reviewed.

RESULTS

All identified patients were African American, relatively young (mean age, 43.8 y) and 5 of the 6 patients were males. Examination of individual macular OCT sections through areas of disproportionately preserved macular thickness invariably demonstrated numerous small cystic cavities within the inner nuclear layer. These microcystic changes were seen in areas of the macula that corresponded with areas of glaucoma-related ganglion cell loss, therefore mimicking the normal appearance of retinal thickness in the macular region. No other retinal pathologies were identified on the macular OCT to account for these changes.

CONCLUSIONS

This study describes microcystic macular changes in mostly young, African American males with moderate to advanced primary open-angle glaucoma. Vitreous adherence to the internal limiting membrane preventing retinal collapse is a proposed mechanism. The disproportionately preserved macular volume may confound the diagnosis of glaucoma in these patients.

Macular Ganglion Cell Analysis Determined by Cirrus HD Optical Coherence Tomography for Early Detecting Chiasmal Compression

Purpose

To evaluate the performance of macular ganglion cell-inner plexiform layer (mGCIPL) measurement with Cirrus high-definition (HD) optical coherence tomography (OCT) for early detection of optic chiasmal compression.

Methods

Forty-six eyes of 46 patients with optic chiasmal compression caused by a pituitary adenoma (PA group), 31 eyes of 31 patients with normal tension glaucoma (NTG group), and 32 eyes of 32 normal participants (control group) were enrolled. The PA group was subdivided into two subgroups, which comprised patients with temporal visual field (VF) defects (perimetric PA group, 34 eyes) and without VF defect (preperimetric PA group, 12 eyes). The mGCIPL thickness and circumpapillary retinal nerve fiber layer (cpRNFL) thickness were measured using Cirrus HD-OCT. We calculated the number of patients who had an abnormal GCA sector map, defined as at least one yellow or red sector.

Results

Eyes in the perimetric PA group had significantly decreased mGCIPL thickness in all sectors. Eyes in the preperimetric PA group had significantly thinner mGCIPL in the superior, superonasal, inferonasal, and inferior sectors than eyes in control group, but no changes in cpRNFL parameters were observed. The mGCIPL thickness in inferonasal area showed the greatest AUC value (0.965), followed by the superonasal area (0.958) for discriminating preperimetric PA group from the control group. A higher reduction rate of mGCIPL thickness was noted in the nasal sector compared to other sectors, which was irrespective of temporal visual field defects. The mGCIPL thickness maps showed superonasal (P = 0.003) and inferonasal thinning in the PA group (P = 0.003), while inferotemporal thinning was revealed in the NTG group (P = 0.001).

Conclusions

Macular GCIPL thickness parameters obtained with the Cirrus HD-OCT were useful in early detection of chiasmal compression and differentiating from NTG by characteristic nasal mGCIPL thinning.

Detection of preperimetric glaucoma using Bruch membrane opening, neural canal and posterior pole asymmetry analysis of optical coherence tomography

We analysed retinal nerve fibre layer (RNFL) defects in eyes with normal circumpapillary RNFL (cpRNFL) thickness using posterior pole asymmetry analysis (PPAA) and investigated the parameters of Bruch membrane opening (BMO) and neural canals using enhanced depth imaging spectral domain optical coherence tomography (EDI-SDOCT). A total of 112 preperimetric glaucomatous eyes of 92 patients were examined to obtain cpRNFL thickness using SD-OCT. Posterior pole asymmetry analysis (PPAA) and central cross-sectional images of the optic nerve head (ONH) were obtained using EDI-SDOCT. Minimal and horizontal distances between the BMO and ONH surfaces (BMOM, BMOH) and the terminal of retinal pigment epithelium (RPE) and ONH surfaces (RPEM, RPEH) were measured. The distribution of the absolute black cells in PPAA was more concentrated in eyes with “U”-shaped neural canals (p < 0.0001). The area under the receiver operating characteristic curve of the ratio of RPEM to RPEH (RPE-R, 0.771 ± 0.08) was significantly larger than the ratio of BMOM to BMOH (BMO-R, 0.719 ± 0.009) for PPAA results. A U-shaped neural canal, lower ratio of RPEM to RPEH, and lower ratio of BMOM to BMOH were considered early indicators of RNFL defects in preperimetric glaucomatous eyes with normal cpRNFL.

Macular thickness analysis for glaucoma diagnosis and management

There is increasing literature regarding the role of macular imaging by optical coherence tomography (OCT) in glaucoma care. Spectral domain OCT (SD-OCT) has allowed for high resolution imaging of the total macula and macular segments. With the use of asymmetry analysis, macular thickness is a measurement that can be used for the detection and progression of glaucoma. Some artifacts seen on retinal nerve fiber layer (rNFL) scans may be overcome by macular SD-OCT imaging. Also, nonglaucomatous optic neuropathies may be more easily identified on macular thickness plots than rNFL scans. Special populations, such as children or myopes, may also have improved glaucoma surveillance using macular SD-OCT. In this review we explore the advantages and pitfalls of macular OCT in glaucoma care and offer an approach on how to use macular thickness scans in clinical practice.

0.54 μm resolution two-photon interference with dispersion cancellation for quantum optical coherence tomography

Quantum information technologies harness the intrinsic nature of quantum theory to beat the limitations of the classical methods for information processing and communication. Recently, the application of quantum features to metrology has attracted much attention. Quantum optical coherence tomography (QOCT), which utilizes two-photon interference between entangled photon pairs, is a promising approach to overcome the problem with optical coherence tomography (OCT): As the resolution of OCT becomes higher, degradation of the resolution due to dispersion within the medium becomes more critical. Here we report on the realization of 0.54 μm resolution two-photon interference, which surpasses the current record resolution 0.75 μm of low-coherence interference for OCT. In addition, the resolution for QOCT showed almost no change against the dispersion of a 1 mm thickness of water inserted in the optical path, whereas the resolution for OCT dramatically degrades. For this experiment, a highly-efficient chirped quasi-phase-matched lithium tantalate device was developed using a novel ‘nano-electrode-poling’ technique. The results presented here represent a breakthrough for the realization of quantum protocols, including QOCT, quantum clock synchronization, and more. Our work will open up possibilities for medical and biological applications

Temporal retinal thickness in eyes with glaucomatous visual field defects using optical coherence tomography

PURPOSE

To evaluate the temporal macular retinal thickness in normal, early, and advanced glaucomatous eyes using optical coherence tomography 3 (OCT-3) and correlate the superior-to-inferior retinal thickness (S/I RT) ratio with corresponding field defects in early and advanced glaucoma patients.

PATIENTS AND METHODS

Forty normal eyes, 40 eyes with early glaucomatous visual field defects, and 33 eyes with advanced visual field defects were included. All participants underwent complete ocular and visual field examinations and OCT-3 imaging on the same day. A 3×3 mm area temporal to the foveal reflex was scanned with the OCT-3 using 6 horizontal, equally spaced raster lines. Retinal thickness was evaluated at points 500 μm apart for each line and S/I RT ratio computed between similar points above and below the fovea for each patient. One-way ANOVA was used to compare S/I RT ratio between the normal, early, and advanced glaucoma eyes.

RESULTS

Average retinal thickness increased progressively, as points temporal to the fovea were scanned. There was a statistically significant difference between the average superior and inferior retinal thickness at points 1500, 2000, and 2500 μm temporal to the fovea in both early and advanced glaucoma eyes (P<0.05) with corresponding significant differences in the S/I RT ratios, when compared with the normal participants (P<0.017).

CONCLUSIONS

OCT-3-generated S/I RT ratios were successfully able to reproduce the structural damage in eyes with early and advanced glaucoma field defects and can complement optic disc scanning protocols in diagnosing glaucoma at an early stage.

Thickness mapping of eleven retinal layers segmented using the diffusion maps method in normal eyes

This study was conducted to determine the thickness map of eleven retinal layers in normal subjects by spectral domain optical coherence tomography (SD-OCT) and evaluate their association with sex and age. Mean regional retinal thickness of 11 retinal layers was obtained by automatic three-dimensional diffusion map based method in 112 normal eyes of 76 Iranian subjects. We applied our previously reported 3D intraretinal fast layer segmentation which does not require edge-based image information but rather relies on regional image texture. The thickness maps are compared among 9 macular sectors within 3 concentric circles as defined by ETDRS. The thickness map of central foveal area in layers 1, 3, and 4 displayed the minimum thickness. Maximum thickness was observed in nasal to the fovea of layer 1 and in a circular pattern in the parafoveal retinal area of layers 2, 3, and 4 and in central foveal area of layer 6. Temporal and inferior quadrants of the total retinal thickness and most of other quadrants of layer 1 were significantly greater in the men than in the women. Surrounding eight sectors of total retinal thickness and a limited number of sectors in layers 1 and 4 significantly correlated with age.

Comparative study of macular ganglion cell complex thickness measured by spectral-domain optical coherence tomography in healthy eyes, eyes with preperimetric glaucoma, and eyes with early glaucoma

PURPOSE

To evaluate the diagnostic accuracy of Topcon 3D spectral-domain optical coherence tomography (SD-OCT) for measuring the macular inner retinal layers and the circumpapillary retinal nerve fiber layer (cpRNFL) in order to detect preperimetric glaucoma.

METHODS

Two hundred four eyes, including 64 healthy eyes, 68 eyes with preperimetric glaucoma, and 72 eyes with early glaucoma were analyzed. Patients had a comprehensive ocular examination including visual field testing and SD-OCT imaging (3D OCT-2000; Topcon Corporation, Tokyo, Japan) in the macular and peripapillary regions. OCT macular scans were segmented into the macular nerve fiber layer (mNFL), ganglion cell layer with the inner plexiform layer (GCIP), and ganglion cell complex (GCC) (composed of the mNFL and GCIP). Ability to discriminate preperimetric glaucoma was assessed using the area under the receiver operating curve for all macular parameters and the cpRNFL.

RESULTS

The median visual field MD was -0.78 ± 1.19 dB for the healthy group, -1.02 ± 1.29 dB for the preperimetric glaucoma group, and -3.08 ± 1.61 dB for the early glaucoma group. There were significant differences between the preperimetric and healthy groups for GCIP and GCC and for almost all cpRNFL thickness parameters (P < 0.05), except for the mNFL and cpRNFL (nasal, 3, 4, 8, 9, and 10 o'clock sectors). The comparisons among the AUCs of the cpRNFL parameters (0.772), the GCIP parameters (0.727) and the GCC parameters (0.720) showed no significant differences in their abilities to detect preperimetric glaucoma.

CONCLUSIONS

The capacity of Topcon 3D-OCT macular intraretinal parameters (GCIP and GCC measurements, not mNFL measurements) to diagnose preperimetric glaucoma is similar to that of the cpRNFL.

Tracking longitudinal retinal changes in experimental ocular hypertension using the cSLO and spectral domain-OCT

PURPOSE

Involvement of the outer retina is controversial in glaucoma. The aim of this study was to test, first, whether the outer retina is affected in experimental ocular hypertension (OHT) and, second, whether whole retinal thickness can be used as a surrogate marker of glaucomatous change.

METHODS

OHT was surgically induced in 20 Dark Agouti rats. Animals were imaged using a modified Spectralis OCT (Heidelberg Engineering, Heidelberg, Germany) at baseline and at 3 and 8 weeks after OHT induction. Measurements were recorded for whole and individual retinal layer thickness in four regions-temporal, superior, nasal, and inferior-around the optic nerve head.

RESULTS

Whole retinal thickness in normal eyes was 172.19 ± 5.17 μm, with no significant regional differences. OHT caused a significant reduction in whole retinal thickness and the outer nuclear layer (ONL) at 3 and 8 weeks (P < 0.05), along with the expected thinning of the retinal nerve fiber layer (RNFL). Whole retinal thickness correlated well with RNFL (P = 0.035) and ONL (P ≤ 0.001) changes. Sensitivity of RNFL and ONL to IOP exposure appeared greater at 3 than at 8 weeks. In addition, regional profiles were significantly altered in the ONL and RNFL after OHT induction.

CONCLUSIONS

Adaptation of the Spectralis OCT enables tracking of structural damage in experimental rat OHT. Here the authors show evidence of glaucomatous damage in the outer retinal layers of this model with significant regional changes and highlight whole retinal thickness in the rat as a useful surrogate marker of inner and outer retinal changes. The authors believe that the OCT data can provide useful information with regard to clinical management.

Do optic discs get "thinner" or "narrower?"

PURPOSE

To survey the literature to determine how the dimensions of the neuroretinal rim are commonly described, and to clarify and standardize the description of changes in the dimensions of the neuroretinal rim in glaucoma.

MATERIALS AND METHODS

Literature review of 275 articles describing the neuroretinal rim in glaucoma and a survey of ophthalmologists describing 2 disc photographs. Frequencies of descriptors of the neuroretinal rim were surveyed, which included "thinning" and "narrowing."

RESULTS

Of the 275 articles, 80 described the neuroretinal rim clinically. Forty-one articles used "thinning" to describe progressive loss of rim tissue in a radial axis, 13 articles used "narrowing" and rest used "width" to describe the characteristics of neuroretinal rim. Of the 295 ophthalmologists, 264 used "thinner," whereas 31 used "narrower" to describe the neuroretinal rim.

CONCLUSIONS

Accurate phenotyping is an essential part of patient care, research, and training. "Thinning" is currently used more commonly than "narrowing" in the literature to describe progressive loss of the neuroretinal rim in a radial axis. It would be appropriate to use "narrowing" for radial loss or decrease in width and "thinning" for decrease in the thickness of the rim.

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.

Macular and retinal nerve fiber layer analysis of normal and glaucomatous eyes in children using optical coherence tomography

PURPOSE

To evaluate macular and nerve fiber layer (NFL) thickness in normal and glaucomatous eyes of children 3 to 17 years old using optical coherence tomography (OCT-3).

DESIGN

Observational cross-sectional study.

METHODS

One hundred fifty-six eyes of 79 patients were enrolled in this institutional study. Fifty-two eyes (33.3%) met criteria for glaucoma and 104 (66.7%) were normal. There were 44 female (55.6%) and 35 male (44.3%) subjects whose ages ranged from 3 to 17 years old (mean 9.5 years, standard deviation 3.5 years, median 9 years). The OCT-3 (Carl Zeiss Meditec, Dublin, California) was used to obtain a fast macular thickness map as well as a fast retinal NFL map of each eye. Data from specific locations around the macula, as well as total macular volume, was analyzed. Similarly, the retinal NFL scan reports average NFL thickness from specific locations around the optic nerve. Data from the superior temporal and inferior temporal sections was analyzed.

RESULTS

There was a statistically significant difference in macular thickness and NFL thickness when normal eyes were compared against those with glaucoma, in all quadrants studied (all P values <or=.001). Mean macular volume was 7.01 +/- 0.42 mm(3) vs 6.57 +/- 0.85 mm(3) for normal vs glaucomatous eyes, respectively (P < .001).

CONCLUSIONS

OCT may prove valuable in the early diagnosis of glaucoma. We have found a difference between normal and glaucomatous eyes in children, similar to that reported in adult studies. Further investigation of OCT testing in children should be considered.

The multifocal pattern electroretinogram in glaucoma

BACKGROUND

The pattern ERG can be used to detect early glaucomatous change, because the response of cells in the inner retina from (typically) 20 degrees -40 degrees of area is reduced before perimetric abnormality is certain. The multifocal pattern electroretinogram (mfPERG) allows analysis of many local regions within this area. The aim of this study was to investigate whether in patients with presumed glaucoma the mfPERG permits diagnosis and discrimination from normals.

METHODS

Measurements on 25 age-related normal eyes were compared to those on 23 eyes with different stages of glaucoma. A RETIScan system was used to generate a stimulus pattern of 19 hexagons, each consisting of six triangles. The triangles pattern-reversed black to white at 75 Hz. Those 19 hexagons were grouped into three stimulus regions: a central field, a middle, and a peripheral ring. The complete array subtended 48 degrees at the eye. The hexagons alternated between black and white, in a temporal pattern that followed a corrected binary m-sequence (length 512, 10 cycles with 39 s each). The amplitudes and latencies of positive responses at approximately 50 ms (P-50) and negative responses at approximately 95 ms (N-95) were analyzed.

RESULTS

In patients with glaucoma the P-50 and N-95 components of the mfPERG were significantly reduced for the central area and both outer rings compared to normal volunteers (p<0.001, Mann-Whitney-U). The most distinct reduction was observed for N-95 and the central ring. Changes in latencies were not conclusive. The reduction of the components increased with the stage of glaucoma. A predictive model for detecting early glaucomatous changes was designed based on P-50-N-95 with 88% sensitivity and 76% specificity.

CONCLUSION

In glaucoma a marked reduction of components, especially centrally is observed in the mfPERG. This hints to an early involvement of central ganglion cells and may be useful for future functional tests.