COVID-19: Special Precautions in Ophthalmic Practice and FAQs on Personal Protection and Mask Selection

The Coronavirus Disease 2019 (COVID-19), caused by severe acute respiratory coronavirus-2, was first reported in December 2019. The World Health Organization declared COVID-19 a pandemic on March 11, 2020 and as of April 17, 2020, 210 countries are affected with >2,000,000 infected and 140,000 deaths. The estimated case fatality rate is around 6.7%. We need to step up our infection control measures immediately or else it may be too late to contain or control the spread of COVID-19. In case of local outbreaks, the risk of infection to healthcare workers and patients is high. Ophthalmic practice carries some unique risks and therefore high vigilance and special precautions are needed. We share our protocols and experiences in the prevention of infection in the current COVID-19 outbreak and the previous severe acute respiratory syndrome epidemic in Hong Kong. We also endeavor to answer the key frequently asked questions in areas of the coronaviruses, COVID-19, disease transmission, personal protection, mask selection, and special measures in ophthalmic practices. COVID-19 is highly infectious and could be life-threatening. Using our protocol and measures, we have achieved zero infection in our ophthalmic practices in Hong Kong and China. Preventing spread of COVID-19 is possible and achievable.

A rabbit model of age-dependant ocular hypertensive response to topical corticosteroids

OBJECTIVE

To investigate the ocular hypertensive response to topical dexamethasone (DEX), rimexolone (RIM), loteprednol etabonate (LOT) and fluorometholone (FML) in rabbits of different ages.

METHODS

Seventy-five rabbits of three age groups (7 weeks, 6 months and 1-year old) received topical administration of 0.1% DEX, 1% RIM, 0.5% LOT, 0.1% FML or balanced salt solution four times daily for 1 month. Intraocular pressure (IOP) was monitored at regular time intervals. After a month, eyes were harvested for histological study with haematoxylin and eosin (H&E), periodic acid Schiff and Masson trichrome staining. Trabecular meshwork changes were graded by masked ocular pathologists.

RESULTS

Topical DEX caused the greatest increase in IOP, followed by RIM and FML. LOT caused the least IOP increase. Similar pattern of IOP response to the four corticosteroids was observed in the three studied age groups. Young rabbits (7 week) were the most responsive to corticosteroids among the age groups. Extracellular matrix thickening in the trabecular meshwork region and loss of trabecular meshwork cells were observed after DEX, FML or RIM treatments.

CONCLUSION

Young rabbits are more susceptible to steroid induced increase in IOP, even for milder steroids such as fluorometholone and rimexolone.

Diagnostic classification of retinal nerve fiber layer measurement in myopic eyes: a comparison between time-domain and spectral-domain optical coherence tomography

PURPOSE

To evaluate and compare the diagnostic classification of retinal nerve fiber layer (RNFL) measurement between time-domain and spectral-domain optical coherence tomography (OCT) in myopic eyes.

DESIGN

Prospective, observational study.

METHODS

A total of 97 eyes from 97 healthy myopic subjects were included. The RNFL in each eye was imaged sequentially with the Stratus OCT and the Cirrus HD-OCT (Carl Zeiss Meditec). With reference to the built-in normative database, the number of abnormal diagnostic classifications (borderline or outside normal limits) in each OCT device was analyzed and compared using the likelihood ratio chi-square test. Multiple logistic regression analysis was performed to evaluate factors associated with abnormal diagnostic classification.

RESULTS

The Cirrus HD-OCT classified a significantly higher percentage of eyes as outside normal limits/borderline in at least 1 clock hour (Stratus, 14.4%/24.8%; Cirrus, 21.6%/34.1%; all P < .01). RNFL measurement at 1 (23.6%) and 2 o'clock (23.5%) of all eyes was the most frequent location classified as abnormal by the Cirrus HD-OCT and the Stratus OCT, respectively. Eyes with smaller optic disc and longer axial length were more likely to have abnormal diagnostic classification.

CONCLUSIONS

In myopic eyes, Cirrus HD-OCT was more likely to have abnormal diagnostic classification than the Stratus OCT.

Genetic variants at 13q12.12 are associated with high myopia in the Han Chinese population

High myopia, which is extremely prevalent in the Chinese population, is one of the leading causes of blindness in the world. Genetic factors play a critical role in the development of the condition. To identify the genetic variants associated with high myopia in the Han Chinese, we conducted a genome-wide association study (GWAS) of 493,947 SNPs in 1088 individuals (419 cases and 669 controls) from a Han Chinese cohort and followed up on signals that were associated with p < 1.0 × 10(-4) in three independent cohorts (combined, 2803 cases and 5642 controls). We identified a significant association between high myopia and a variant at 13q12.12 (rs9318086, combined p = 1.91 × 10(-16), heterozygous odds ratio = 1.32, and homozygous odds ratio = 1.64). Furthermore, five additional SNPs (rs9510902, rs3794338, rs1886970, rs7325450, and rs7331047) in the same linkage disequilibrium (LD) block with rs9318086 also proved to be significantly associated with high myopia in the Han Chinese population; p values ranged from 5.46 × 10(-11) to 6.16 × 10(-16). This associated locus contains three genes-MIPEP, C1QTNF9B-AS1, and C1QTNF9B. MIPEP and C1QTNF9B were found to be expressed in the retina and retinal pigment epithelium (RPE) and are more likely than C1QTNF9B-AS1 to be associated with high myopia given the evidence of retinal signaling that controls eye growth. Our results suggest that the variants at 13q12.12 are associated with high myopia.

Association of hemopexin in tear film and conjunctival macrophages with vernal keratoconjunctivitis

OBJECTIVE

Vernal keratoconjunctivitis (VKC) is a chronic allergic inflammatory disease with unclear etiology and pathogenesis. We investigated the tear film proteome of patients with VKC to understand the pathologic characteristics of VKC.

METHODS

Tear samples were collected from healthy volunteers and patients with VKC. Electrophoresis was performed to display the tear proteomic profiles according to VKC severity. The identities of differentially expressed proteins were analyzed by mass spectrometry and quantified by enzyme-linked immunosorbent assay. Impression cytology was performed on VKC conjunctival samples to demonstrate the cellular protein expression. Allergic sensitization was performed in mice to study the pathologic role of these proteins in VKC.

RESULTS

Hemopexin, an inflammatory protein, was elevated in the tear film of patients with VKC. The increased hemopexin concentration in VKC tears was significantly associated with disease severity. Impression cytology showed specific high hemopexin expression in dekeratinized conjunctival epithelium and necrotic macrophages in patients with VKC. Immunohistochemical examination of normal lacrimal tissues from mice showed that hemopexin was not expressed in any lacrimal apparatus. Under systemic and topical sensitization and challenge using hemopexin in mice, the affected eye had mild to moderate bead discharge, chemosis, and edema with excessive macrophage infiltration and conjunctival necrosis.

CONCLUSION

An association exists between tear hemopexin and the development and pathologic effects of VKC.

CLINICAL RELEVANCE

Increased hemopexin may have a role in the development of VKC.

Evaluation of retinal nerve fiber layer progression in glaucoma: a comparison between the fast and the regular retinal nerve fiber layer scans

OBJECTIVE

To compare the performance of the fast (256 A-scans in each scan circle) and the regular (512 A-scans in each scan circle) retinal nerve fiber layer (RNFL) scan protocols for detection of glaucoma progression using the Stratus optical coherence tomography (OCT) device (Carl Zeiss Meditec, Dublin, CA).

DESIGN

Retrospective, longitudinal study.

PARTICIPANTS

One hundred twenty-nine eyes from 72 glaucoma patients.

METHODS

All patients had been followed up for 2.9 to 6.1 years with a median follow-up of 4 months. All eyes had at least 4 serial RNFL measurements obtained with both the fast and the regular RNFL scans. Visual field (VF) assessment was performed on the same day as RNFL imaging. Retinal nerve fiber layer thickness and VF progression were evaluated with linear regression analysis against age. The mean rate of average RNFL thickness reduction was estimated with linear mixed modeling.

MAIN OUTCOME MEASURES

The agreement of progression detection and the rate of change of RNFL thicknesses.

RESULTS

A total of 1373 fast and 1373 regular RNFL scans and 1236 VF tests were analyzed. With reference to the average RNFL thickness, the fast RNFL scan detected more eyes with progression (21 eyes from 19 patients vs. 15 eyes from 13 patients) than the regular scan at a comparable level of specificity (96.9% vs. 96.1%). More eyes were found to have increasing RNFL thickness with age at individual clock hours (except for 3, 5, 6, and 11 o'clock) when the measurements were obtained with the regular scan. The agreement between the fast and the regular scan for detection of RNFL progression was fair to moderate, with κ values ranging between 0.14 and 0.49. The rate of average RNFL thickness progression was -1.01 μm per year for the fast RNFL scan and -0.77 μm per year for the regular scan.

CONCLUSIONS

The choice of scan protocols in the Stratus OCT has a significant impact in the evaluation of RNFL progression. The fast RNFL scan seems to be preferable to follow RNFL damage in glaucoma.

Dynamic analysis of iris configuration with anterior segment optical coherence tomography

PURPOSE

To evaluate dynamic changes in iris configuration and their association with anterior chamber angle width by using anterior segment optical coherence tomography (ASOCT).

METHODS

Forty-six normal subjects with open angles and 40 with narrow angles (Shaffer grade < or =2 in three or more quadrants during dark room gonioscopy) were analyzed. The dynamic ASOCT dark-light changes of iris bowing were captured with real-time video recording and nasal iris bowing, nasal anterior chamber angle, and pupil diameter were measured in serial image frames selected from the video capture. The associations between iris bowing, iris thickness, anterior chamber depth (ACD), age, anterior chamber angle, and pupillary diameter measurements were evaluated with univariate and multivariate regression analyses.

RESULTS

The relationship between iris bowing and pupil diameter was largely linear, with three dynamic patterns observed: (1) convex-to-convex (iris remains convex in dark and light); (2) concave-to-convex (iris changes from concave to convex from light to dark); and (3) concave-to-concave (iris remains concave in dark and light). All the subjects with narrow angles had convex-to-convex anatomy, although 43% of the subjects with open angles also demonstrated this pattern. These individuals were older and had shorter axial length (both with P < 0.001). Older age (r = -0.352, P = 0.001), smaller ACD (r = 0.382, P < 0.001), and smaller difference in angle opening distance in light and dark (r = 0.472, P < 0.001) were associated with smaller differences in iris bowing in the light and dark. ACD and iris bowing were independently associated with anterior chamber angle width.

CONCLUSIONS

Independent of ACD, iris bowing is an important biometric parameter that determines angle width. Investigation of iris dynamics may offer a new perspective in understanding the risk and mechanism of primary angle closure.

Ethnicity-based subgroup meta-analysis of the association of LOXL1 polymorphisms with glaucoma

PURPOSE

To investigate the association and ethnic heterogeneity of lysyl oxidase-like 1 (LOXL1) single nucleotide polymorphisms (SNPs) with exfoliation syndrome (XFS)/exfoliation glaucoma (XFG) and other types of glaucoma.

METHODS

We performed meta-analysis and ethnicity-based subgroup analyses according to published studies. Allele and genotype frequencies of SNPs rs1048661, rs2165241, and rs3825942 were extracted for analysis in Reviewer Manager: (1) comparison of the allelic distributions between XFS and XFG, (2) allelic association of LOXL1 SNPs with XFS/XFG, (3) associations in homozygote, heterozygote, and dominant and recessive models, and (4) allelic association with primary open angle glaucoma (POAG).

RESULTS

In total 24 reported articles were retrieved, including Caucasian, African, Japanese, Indian, and Chinese populations. There was no significant difference in the distributions of rs1048661, rs2165241, and rs3825942 between XFS and XFG. The G allele of rs3825942 was the common at-risk allele for XFS/XFG in all populations with a total odds ratio (OR) of 10.89. The total homozygote OR of rs3825942 was 9.06 for XFS/XFG combined, but the total heterozygote OR was not significant. We also found that in the recessive model, the total OR was 14.70. There was no association of the three SNPs with POAG.

CONCLUSIONS

The association of rs3825942, but not rs2165241 or rs1048661, with XFS/XFG is consistent in different ethnic populations in the recessive model. LOXL1 is not associated with POAG in all study populations.

Evaluation of retinal nerve fiber layer progression in glaucoma: a study on optical coherence tomography guided progression analysis

PURPOSE

To evaluate optical coherence tomography (OCT) retinal nerve fiber layer thickness (RNFLT) measurement for glaucoma progression analysis.

METHODS

One hundred sixteen eyes of 64 patients with glaucoma who were observed within a period of 5 years were included. All eyes had at least four serial RNFL measurements obtained with the Stratus OCT (Carl Zeiss Meditec, Dublin, CA) and with the first and last measurements separated by at least 3 years. Visual field (VF) testing was performed on the same day as RNFL imaging. Serial average RNFLTs were evaluated with guided progression analysis (GPA). VF progression was assessed with trend analysis of the visual field index (VFI). Factors associated with the rate of change in RNFLT were examined with a linear mixed model.

RESULTS

A total of 1101 OCT scans and 1029 VFs were analyzed. Twenty-one and 22 eyes had progression according to RNFL and VF measurements, respectively, and 3 eyes had progression according to both measurements. The rate of change in VFI and RNFLT ranged between -0.5% and -7.2% per year (median loss, -3.0%/y) and between -1.2 and -15.4 microm per year (median loss, -3.3 microm/y), respectively. The sector at seven o'clock (right eye orientation) was the most frequent location that showed progression. A greater baseline RNFLT was associated with an increased rate of reduction of RNFLT (P = 0.034).

CONCLUSIONS

OCT GPA offers a new approach to augment glaucoma progression analysis. The rate of RNFLT thinning was variable among patients with glaucoma, with an increased rate of loss in patients with a higher baseline RNFLT.

AC and AG dinucleotide repeats in the PAX6 P1 promoter are associated with high myopia

PURPOSE

The PAX6 gene, located at the reported myopia locus MYP7 on chromosome 11p13, was postulated to be associated with myopia development. This study investigated the association of PAX6 with high myopia in 379 high myopia patients and 349 controls.

METHODS

High myopia patients had refractive errors of -6.00 diopters or greater and axial length longer than 26 mm. Control subjects had refractive errors less than -1.00 diopter and axial length shorter than 24 mm. The P1 promoter, all coding sequences, and adjacent splice-site regions of the PAX6 gene were screened in all study subjects by polymerase chain reaction and direct sequencing. PAX6 P1 promoter-luciferase constructs with variable AC and AG repeat lengths were prepared and transfected into human ARPE-19 cells prior to assaying for their transcriptional activities.

RESULTS

No sequence alterations in the coding or splicing regions showed an association with high myopia. Two dinucleotide repeats, (AC)(m) and (AG)(n), in the P1 promoter region were found to be highly polymorphic and significantly associated with high myopia. Higher repeat numbers were observed in high myopia patients for both (AC)(m) (empirical p = 0.013) and (AG)(n) (empirical p = 0.012) dinucleotide polymorphisms, with a 1.327-fold increased risk associated with the (AG)(n) repeat (empirical p = 0.016; 95% confidence interval: 1.059-1.663). Luciferase-reporter analysis showed elevated transcription activity with increasing individual (AC)(m) and (AG)(n) and combined (AC)(m)(AG)(n) repeat lengths.

CONCLUSIONS

Our results revealed an association between high myopia and AC and AG dinucleotide repeat lengths in the PAX6 P1 promoter, indicating the involvement of PAX6 in the pathogenesis of high myopia.

Retinal nerve fiber layer imaging with spectral-domain optical coherence tomography: a variability and diagnostic performance study

OBJECTIVE

To evaluate and compare the retinal nerve fiber layer (RNFL) measurement variability, diagnostic sensitivity and specificity for glaucoma detection, and strength of the structure-function association obtained with a spectral-domain optical coherence tomography (OCT) device (Cirrus HD-OCT; Carl Zeiss Meditec, Inc., Dublin, CA) and a time-domain OCT device (Stratus OCT; Carl Zeiss Meditec, Inc.).

DESIGN

Prospective, cross-sectional study.

PARTICIPANTS

Ninety-seven normal subjects and 83 glaucoma patients.

METHODS

One eye from each subject was imaged with Cirrus HD-OCT and Stratus OCT. Sixteen and 31 normal eyes were selected randomly to evaluate intravisit repeatability and intervisit reproducibility, respectively. The agreement of RNFL measurements was evaluated with Bland-Altman plots. The diagnostic sensitivity and specificity was examined with the area under the receiver operating characteristic curve (AUC). The association between average RNFL thickness and visual field sensitivity was evaluated with a second-order regression model.

MAIN OUTCOME MEASURES

Retinal nerve fiber layer measurement variability, AUC, and coefficient of determination (R(2)).

RESULTS

The intravisit repeatability of Cirrus HD-OCT ranged between 5.12 and 15.02 mum, and the intervisit reproducibility ranged between 4.31 and 22.01 mum. The intervisit variabilities of sectoral and average RNFL thicknesses were lower in Cirrus HD-OCT compared with Stratus OCT with significant differences at 1, 3, 4, and 8 to 11 o'clock (P< or =0.021). There were proportional biases of RNFL measurements between the 2 OCT devices. The difference of RNFL thicknesses increased with the means. The average (AUC, 0.962 for Cirrus HD-OCT and 0.956 Stratus OCT), superior (AUC, 0.963 and 0.950, respectively), and inferior (AUC, 0.949 and 0.931, respectively) RNFL thicknesses demonstrated the greatest AUCs in both OCT devices with no significant difference detected between the respective measurements (P> or =0.120). The strength of the structure-function association was comparable between Cirrus HD-OCT (R(2) = 0.580) and Stratus OCT devices (R(2) = 0.623; P = 0.918).

CONCLUSIONS

Although the diagnostic performance and the strength of the structure-function association were comparable between Cirrus HD-OCT and Stratus OCT RNFL measurements, Cirrus HD-OCT demonstrated lower measurement variability compared with Stratus OCT with significant differences at 1, 3, 4, and 8 to 11 o'clock. The poor agreement was likely related to the different inherent characteristics of the 2 OCT systems.

Predictors of atypical birefringence pattern in scanning laser polarimetry

AIM

To evaluate predictors of atypical birefringence patterns (ABP) observed in scanning laser polarimetry.

METHODS

A total of 179 eyes from 82 normal subjects and 97 glaucoma patients were included. The retinal nerve fibre layer in each eye was imaged sequentially with GDx variable corneal compensation (VCC) and GDx enhanced corneal compensation (ECC) (Carl Zeiss Meditec, Dublin, California). The associations between the typical scan score (TSS) and age, axial length, spherical error, parapapillary atrophy (PPA) and visual-field mean deviation (MD) were evaluated with univariate and multivariate regression analyses.

RESULTS

23.5% (42/179) and 5.0% (9/179) of subjects had ABP (TSS<80) with GDx VCC and GDx ECC, respectively. For both GDx VCC and ECC, the TSS was significantly correlated with age, axial length, spherical error and PPA, but not with visual-field MD. After adjusting the effect of covariates, the axial length/spherical error and PPA were significantly associated with GDx VCC TSS, whereas the axial length/spherical error was the only predictor for GDx ECC TSS. Myopic eyes were more likely to develop ABP in both GDx VCC and ECC.

CONCLUSIONS

Axial length or spherical error is a significant predictor for ABP with both GDx VCC and GDx ECC. Caution should be exercised in interpreting the results of scanning laser polarimetry in eyes with a long axial length or myopia.

Unilateral ptosis correction with mersilene mesh frontalis sling in infants: thirteen-year follow-up report

PURPOSE

To assess surgical, visual, refractive, and aesthetic outcomes 13 years after mersilene mesh frontalis sling (MMFS) operation for severe unilateral congenital ptosis performed in 10 infants before 1 year of age.

METHODS

Longitudinal follow-up of an interventional case series by structured ocular examinations, external photographs, and questionnaire-based interviews.

RESULTS

Mean age at surgery was 6.9+/-2.7 months. After a mean follow-up of 13.0+/-0.6 years, one patient (10%) had recurrent ptosis with the upper lid 2 mm below the superior limbus at 3 months postoperatively. Best-corrected visual acuities were within two Snellen lines between the two eyes in all patients. Astigmatic errors were 1.20+/-1.00 D and 1.10+/-1.70 D between operated and unoperated eyes. Four patients had 2 mm lid lag on down-gaze and one of them had 2 mm lagophthalmos. Mean satisfaction scores (scale of 1 to 100) for lid position, cosmesis, function, and to the procedure were 83.3+/-11.8, 77.0+/-22.9, 89.4+/-5.5, and 86.8+/-6.3, respectively. No case of overcorrection, sling extrusion, stitch granuloma, or exposure keratopathy was noted.

CONCLUSIONS

In view of the low recurrence rate (10%) and absence of serious complication or need for revision after 13 years, the use of MMFS seems effective and feasible in infants less than 1 year old. Achieving compatible long-term stability, satisfactory aesthetic, and visual outcomes, MMFS may offer an alternative to delaying operations for autogenous fascia lata harvesting in infants requiring early ptosis correction.

Quantitative assessment of optic nerve head morphology and retinal nerve fibre layer in non-arteritic anterior ischaemic optic neuropathy with optical coherence tomography and confocal scanning laser ophthalmoloscopy

BACKGROUND/AIMS

To compare the optic disc parameters between patients with non-arteritic anterior ischaemic optic neuropathy (NAION) and normal controls, using optical coherence tomography (OCT) and Heidelberg Retinal Tomograph III (HRT), and to evaluate the structure-function relationship in NAION eyes.

METHODS

Both eyes of 22 patients with typical unilateral NAION of > or =6 months' duration and 52 eyes from 52 randomly selected normal subjects underwent Humphrey visual field (HVF) examination and measurement of optic disc and retinal nerve fibre layer thickness (RNFLT).

RESULTS

For the NAION-affected eyes, NAION fellow eyes and normal controls, the ocular magnification-corrected OCT disc areas were respectively 1.849 (SD 0.343) mm(2), 1.809 (0.285) mm(2) and 1.964 (0.386) mm(2); the cup areas were 0.246 (0.187) mm(2), 0.172 (0.180) mm(2) and 0.469 (0.332) mm(2). On HRT, the disc areas were 2.11 (0.38) mm(2), 2.06 (0.40) mm(2) and 2.16 (0.42) mm(2); and the cup areas were 0.28 (0.34) mm(2), 0.25 (0.18) mm(2) and 0.48 (0.32) mm(2). On both OCT and HRT, the cup areas and cup-disc area ratios (CDAR) of both eyes of NAION patients were significantly smaller than controls (p< or =0.01), but the disc areas were not (p> or =0.21). There was a significant correlation between HVF mean deviation and OCT RNFLT (r = 0.44, p = 0.04) but not with HRT RNFLT (p = 0.30) in NAION-affected eyes.

CONCLUSION

NAION patients have smaller optic cups and CDARs in both eyes compared with controls. A larger sample size is necessary to demonstrate if disc size affects the risk of developing NAION. The NAION-affected eyes' OCT RNFLT correlated with HVF mean deviation but the HRT RNFLT did not.

Intravitreal bevacizumab (Avastin) for myopic choroidal neovascularisation: 1-year results of a prospective pilot study

AIM

The aim of the study was to examine the 1-year results of intravitreal bevacizumab for myopic choroidal neovascularisation (CNV).

METHODS

Twenty-nine eyes of 29 patients with myopic CNV were prospectively recruited to receive three initial monthly intravitreal bevacizumab injections. Three additional monthly injections were performed in eyes with persistent or recurrent CNV after 3 months.

RESULTS

The mean spherical equivalent refractive error was -10.0 D. Sixteen eyes had previous photodynamic therapy (PDT) and 13 eyes had no prior PDT. All patients completed follow-up at 1 year. Following the initial three bevacizumab injections, 27 (93.1%) eyes had angiographic closure and two (6.9%) required further treatment. Two additional patients required re-treatment for CNV recurrence between 6 and 9 months. The mean baseline logarithm of the minimum angle of resolution (logMAR best-corrected visual acuity) was 0.62 (20/83), which improved to 0.38 (20/48) at 12 months (p<0.001). The mean visual improvement was 2.4 lines and 21 (72.4%) eyes had improvement of > or =2 lines. Optical coherence tomography showed significant reduction in central foveal thickness following treatment. Eyes without previous PDT were more likely to gain > or =2 lines after treatment than eyes that had previous PDT (p = 0.010).

CONCLUSIONS

The 1-year outcomes confirmed the results of previous short-term studies that intravitreal bevacizumab is effective for myopic CNV, with a high proportion of patients sustaining visual gain after treatment.

Comparative study of central corneal thickness measurement with slit-lamp optical coherence tomography and visante optical coherence tomography

PURPOSE

To evaluate the repeatability and reproducibility of central corneal thickness (CCT) measurements obtained by 2 anterior segment optical coherence tomography (OCT) imaging systems and to examine their agreements with ultrasound pachymetry.

DESIGN

Observational cross-sectional study.

PARTICIPANTS

Fifty eyes from 50 healthy normal subjects were recruited.

METHODS

In one randomly selected eye in each subject, CCT was measured by slit-lamp OCT (SLOCT), Visante OCT, and ultrasound pachymetry. For anterior segment OCT measurements, both automatic and manual CCTs were obtained. Twenty-five of the 50 subjects were invited for 2 more visits within a week to evaluate repeatability and reproducibility of CCT measurement.

MAIN OUTCOME MEASURES

Central corneal thickness measurement obtained by the 3 methods and their agreements. Intrasession and intersession within-subject standard deviation (S(w)), precision (1.96xS(w)), coefficient of variation (CV(w)) (100xS(w)/overall mean), and intraclass correlation coefficient (ICC) were calculated to evaluate repeatability and reproducibility.

RESULTS

Good repeatability and reproducibility were found for both automatic and manual CCT measurements obtained by SLOCT and Visante OCT. For intrasession repeatability, CV(w) and ICC values ranged between 0.9% and 1.2% and 0.96 and 0.98, respectively. For intersession reproducibility, the respective CV(w) and ICC values ranged between 1.2% and 1.4% and 0.94 and 0.96. Although no significant difference was found between automatic/manual SLOCT measurements and ultrasound pachymetry, automatic Visante OCT CCT (535.7+/-30.2 microm) was significantly less than CCT with ultrasound pachymetry (550.3+/-31.14 microm) (P<0.001). In contrast, manual Visante OCT measurement (558.8+/-32.8 microm) was slightly higher than ultrasound pachymetry (P<0.001). Nevertheless, SLOCT and Visante OCT measurement of CCT had 95% limits of agreement comparable to that of ultrasound pachymetry. The best agreement was observed in the manual SLOCT measurement (95% limits of agreement between -15.5 and 11.7 microm).

CONCLUSIONS

Both SLOCT and Visante OCT automatic and manual CCT measurements were reliable and showed comparable agreement with ultrasound pachymetry. Although the 2 anterior segment OCT imaging systems have similar design and working principles, clinicians should be aware of the differences in CCT measurement between the 2 anterior segment OCTs.

Correlation of previous acute angle-closure attack with extent of synechial angle closure in chronic primary angle-closure glaucoma patients

AIM

To document any correlation between previous acute angle-closure attack and the extent of synechial angle closure in chronic primary angle-closure glaucoma (PACG) patients.

METHODS

Consecutive cases of chronic PACG with patent peripheral iridotomy had gonioscopy performed. The extents of synechial angle closure of those chronic PACG eyes with previous documented acute angle-closure attack were compared to those eyes without such a history.

RESULTS

A total of 102 chronic PACG eyes of 102 patients were recruited. Twenty-seven eyes (26.5%) had a previous documented acute angle closure, while 75 eyes (73.5%) did not. The mean extent of synechial angle closure +/-1 SD was 307+/-68 degrees (range, 150-360 degrees) in those chronic PACG eyes with a history of previous acute angle closure, compared to 266+/-89 degrees (range, 90-360 degrees) in those chronic PACG eyes without such a history (P=0.03, Student's t-test). There were no statistically significant differences between the two groups in age, LogMAR visual acuity, intraocular pressure (IOP), number of glaucoma eye drops, vertical cup-to-disk ratio, mean deviation or pattern SD in Humphrey automated perimetry, and anterior chamber depth (P>0.05).

CONCLUSION

Previous acute angle-closure attack correlated with more extensive synechial angle closure in chronic PACG patients in this study.

Anterior chamber angle measurement with anterior segment optical coherence tomography: a comparison between slit lamp OCT and Visante OCT

PURPOSE

To compare anterior chamber angle measurements obtained from two anterior segment optical coherence tomography (OCT) instruments and to evaluate their agreements and interobserver reproducibility.

METHODS

Forty-nine eyes from 49 healthy normal subjects were studied. The anterior chamber angle was imaged with the Visante anterior segment OCT (Carl Zeiss Meditec, Dublin, CA) and the slit lamp OCT (SLOCT, Heidelberg Engineering, GmbH, Dossenheim, Germany) on one randomly selected eye in each subject and measured by two independent observers. The angle-opening distance (AOD 500), the trabecular-iris angle (TIA 500), and the trabecular-iris space area (TISA 500) at the nasal and temporal angles were measured. The agreements between SLOCT and Visante OCT measurements and the interobserver reproducibility were evaluated.

RESULTS

The mean nasal/temporal anterior chamber angles measured by Visante OCT and SLOCT were 527 +/- 249/572 +/- 275 microm (AOD), 0.180 +/- 0.091/0.193 +/- 0.102 mm(2) (TISA), and 38.1 +/- 12.3/39.6 +/- 13.2 degrees (TIA); and 534 +/- 234/628 +/- 254 microm (AOD), 0.191 +/- 0.089/0.217 +/- 0.093 mm(2)(TISA), and 37.8 +/- 10.1/40.6 +/- 10.7 degrees (TIA), respectively. No significant difference was found between Visante OCT and SLOCT measurements except the temporal TISA (P = 0.034). The interobserver coefficient of variation ranged between 4.4% and 7.8% for Visante OCT and 4.9% and 7.0% for SLOCT. The spans of 95% limits of agreement of the nasal/temporal angle measurements between Visante OCT and SLOCT were 437/531 mm(2), 0.174/0.186 mm(2), and 25.3/28.0 degrees for AOD, TISA, and TIA, respectively.

CONCLUSIONS

Although Visante OCT and SLOCT demonstrate high interobserver reproducibility for anterior chamber angle measurements, their agreement was poor.

Effects of the duration of initial oral corticosteroid treatment on the recurrence of inflammation in Vogt-Koyanagi-Harada disease

PURPOSE

To evaluate the effects of the duration of oral corticosteroid treatment on the recurrence of inflammation in Vogt-Koyanagi-Harada (VKH) disease.

METHODS

Retrospective analysis of 35 VKH patients who received oral corticosteroid during the first attack of VKH with a minimum follow-up of 6 months. Patients were divided into two groups on the basis of the oral corticosteroid treatment duration of less than 6 months or 6 months or more. Kaplan-Meier survival and Cox-regression analyses were carried out to compare the recurrence rates of inflammation in the two groups.

RESULTS

The mean age of onset was 42.5 years and the mean follow-up duration was 3.6 years. During the follow-up period, 10 (58.8%) of the 17 patients who received oral corticosteroid for less than 6 months compared with 2 (11.1%) of the 18 patients who had treatment for 6 months or more developed recurrence of inflammation (P=0.003). Cox-regression analysis showed that the duration of oral corticosteroid treatment for less than 6 months was the only significant risk factor for recurrence of VKH after adjustment for age, gender, and the initial dosage of oral corticosteroid treatment (adjusted odds ratio=8.8, P=0.008). Patients who received oral corticosteroid treatment for less than 6 months were also more likely to have one eye with visual acuity of 20/200 or worse (P=0.016).

CONCLUSIONS

Early withdrawal of oral corticosteroid is associated with increased risk of recurrence of VKH and worse visual prognosis. Oral corticosteroid should be tapered off slowly and maintained for at least 6 months for the treatment of acute VKH.

Relationship between retinal nerve fiber layer measurement and signal strength in optical coherence tomography

PURPOSE

To examine the relationship between signal strength and retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT).

DESIGN

Observational cross-sectional study.

PARTICIPANTS

Forty normal subjects were recruited.

METHODS

Retinal nerve fiber layer (RNFL) thickness was measured by Stratus OCT (Carl Zeiss Meditec, Dublin, CA). In each eye, the focusing knob was adjusted to obtain 6 images with different signal strengths ranging from 5 to 10. The relationships between signal strength and RNFL thickness were examined using the Spearman correlation coefficient. The differences of RNFL thicknesses were compared with repeated-measures analysis of variance.

MAIN OUTCOME MEASURES

Retinal nerve fiber layer thicknesses measured at different signal strengths.

RESULTS

Significant differences were observed between measurements obtained at signal strength of 10 and those obtained with signal strength of less than 10 at the superior, nasal, and temporal clock hours. RNFL thickness generally increased with the signal strength, with significant correlations found with the total average, superior, and nasal clock hours RNFL thicknesses.

CONCLUSIONS

Optical coherence tomography RNFL measurements vary significantly with signal strength. Obtaining the maximal possible signal strength is recommended for RNFL thickness measurement.

PI3K/akt, JAK/STAT and MEK/ERK pathway inhibition protects retinal ganglion cells via different mechanisms after optic nerve injury

Recently we unexpectedly found that PI3K/akt, JAK/STAT and MEK/ERK pathway inhibitors enhanced retinal ganglion cell (RGC) survival after optic nerve (ON) axotomy in adult rat, a phenomenon contradictory to conventional belief that these pathways are pro-survival. In this study we showed that: (i) the RGC protection was pathway inhibition-dependent; (ii) inhibition of PI3K/akt and JAK/STAT, but not MEK/ERK, activated macrophages in the eye, (iii) macrophage removal from the eye using clodronate liposomes significantly impeded PI3K/akt and JAK/STAT inhibition-induced RGC survival and axon regeneration whereas it only slightly affected MEK/ERK inhibition-dependent protection; (iv) in the absence of recruited macrophages in the eye, inhibition of PI3K/akt or JAK/STAT did not influence RGC survival; and (v) strong PI3K/akt, JAK/STAT and MEK/ERK pathway activities were located in RGCs but not macrophages after ON injury. In retinal explants, in which supply of blood-derived macrophages is absent, MEK/ERK inhibition promoted RGC survival whereas PI3K/akt or JAK/STAT inhibition had no effect on RGC viability. However, MEK/ERK inhibition exerted opposite effects on the viability of purified adult RGCs at different concentrations in vitro, suggesting that this pathway may be bifunctional depending on the level of pathway activity. Our data thus demonstrate that inhibition of the PI3K/akt or JAK/STAT pathway activated macrophages to facilitate RGC protection after ON injury whereas the two pathways per se did not modulate RGC viability under the injury conditions (in the absence of the pathway activators). In contrast, the MEK/ERK pathway inhibition protected RGCs via macrophage-independent mechanism(s).

Dynamic analysis of dark-light changes of the anterior chamber angle with anterior segment OCT

PURPOSE

To describe the use of anterior segment optical coherence tomography (OCT) in studying the dynamic dark-light changes of the anterior chamber angle.

METHODS

Thirty-seven normal subjects with open angles on dark-room gonioscopy and 18 subjects with narrow angles were analyzed. The dynamic dark-light changes of the anterior-chamber angle were captured with real-time video recording. The angle opening distance (AOD500) and trabecular iris space area (TISA500) of the nasal angle and the pupil diameter in each of the representative serial images were measured. Linear regression analysis was performed to investigate the association between AOD500/TISA500 and pupil diameter. Demographic and biometry measurements associated with the AOD difference (AOD500((light)) - AOD500((dark))) and TISA difference (TISA500((light)) - TISA500((dark))) were analyzed with univariate and multivariate regression models.

RESULTS

The AOD500/TISA500 measured in the light in the open-angle and the narrow-angle groups were 694 +/- 330 microm/0.24 +/- 0.10 mm(2) and 265 +/- 78 microm/0.10 +/- 0.03 mm(2), respectively. These values were significantly greater than the AOD500/TISA500 measured in the dark (492 +/- 265 microm/0.16 +/- 0.08 mm(2) and 119 +/- 82 microm/0.05 +/- 0.04 mm(2), respectively, all with P < 0.001). The ranges of the AOD/TISA difference were 13 to 817 microm/0.011 to 0.154 mm(2), with an average of 180 microm/0.073 mm(2). Multivariate regression analysis identified a positive correlation between anterior chamber depth and the AOD/TISA difference. Fifty eyes showed significant correlations between AOD/TISA and pupil diameter, whereas one eye showed no association. Four eyes in the narrow angle group developed appositional angle closure in the dark.

CONCLUSIONS

The dynamic dark-light changes of the anterior chamber angle can be imaged and analyzed with anterior segment OCT. Although the angle width generally decreased linearly with increasing pupil diameter, the differences of the angle width measured in the dark and in the light varied substantially among individuals.

Optic disc measurements in myopia with optical coherence tomography and confocal scanning laser ophthalmoscopy

PURPOSE

To evaluate the relationships between optic disc measurements, obtained by an optical coherence tomograph and a confocal scanning laser ophthalmoscope, and myopia.

METHODS

One hundred thirty-three eyes from 133 healthy subjects with mean spherical equivalent -6.0 +/- 4.2 D (range, -13.13 to +3.25 D) were analyzed. Optic disc measurements including disc area, rim area, cup area, cup-to-disc area, and vertical and horizontal ratios were obtained with an optical coherence tomograph (StratusOCT; Carl Zeiss Meditec Inc., Dublin, CA) and a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph, HRT 3; Heidelberg Engineering, GmbH, Dossenheim, Germany). The modified axial length method derived from prior published work was used to correct the OCT measurements for ocular magnification. Bland-Altman plots were used to evaluate the agreement for each optic disc parameter. Associations between optic disc area and axial length/spherical equivalent were evaluated by linear regression analysis.

RESULTS

Disc area increased with the axial length/negative spherical equivalent in the HRT and the corrected OCT measurements although opposite directions of associations were found when the OCT measurements were not corrected for magnification. The difference of the corrected OCT and HRT disc area (corrected OCT disc area minus HRT disc area) was correlated with the axial length (r = 0.195, P = 0.025). When the ametropia was limited to -8.0 to +4.0 D, the correlations became insignificant in the HRT. Using the corrected OCT measurements, disc area, rim area, and cup area, cup-to-disc area, and cup-to-disc horizontal and vertical ratios were significantly larger than those measured by the HRT, with a span of 95% limits of agreement at 1.99, 1.33, and 1.86 mm(2) for the areas, 0.34, 0.53, and 0.58 for the ratios, respectively.

CONCLUSIONS

While optic disc area generally increased with the axial length and myopic refraction, the HRT measurements demonstrated that optic disc size was largely independent of axial length and refractive error between -8 and +4 D. OCT may overestimate optic disc size in myopic eyes and results in poor agreement between the two instruments.

American Chinese Glaucoma Imaging Study: A Comparison of the Optic Disc and Retinal Nerve Fiber Layer in Detecting Glaucomatous Damage

PURPOSE

To compare the relationships between optic nerve structural measures and visual function, as well as the diagnostic sensitivity for glaucoma detection between the retinal nerve fiber layer (RNFL) and neuroretinal rim measurements.

METHODS

A total of 101 normal and 156 glaucomatous eyes of 257 enrolled subjects were examined. RNFL thickness was measured by optical coherence tomography, and the neuroretinal rim (rim area, rim/disc area, and rim volume) was measured with a confocal scanning laser ophthalmoscope. The relationship between the structural measures and visual field sensitivity was evaluated with linear and non-linear-regression (quadratic and logarithmic) models. The coefficient of determination (R2) was calculated, and the regression models were compared with Alkaike's information criteria and the F test. The diagnostic sensitivity for glaucoma detection in each structural measure was determined by the area under the receiver operating characteristic curve (AUC).

RESULTS

The relationship of the RNFL, rim area, rim/disc area, and rim volume with visual function was best described with nonlinear regression models (quadratic regression for the RNFL [R2 = 0.383]), rim area [R2 = 0.303]), and rim/disc area [R2 = 0.265]; and logarithmic regression for rim volume [R2 = 0.175]). The change of visual sensitivity at each level of structural damage was highest for the RNFL. The AUC for the RNFL also was higher than the neuroretinal rim measures. In this study population, at 90% specificity, the diagnostic sensitivities for detecting glaucomatous damage was 82.7%, 67.3%, 67.3%, and 52.6% for the RNFL, rim area, rim/disc area, and rim volume, respectively. (These values would apply only to a group with inclusion criteria and disease severity similar to those of the present cohort.)

CONCLUSIONS

The RNFL showed a stronger structure-function association and a higher diagnostic sensitivity for glaucoma detection than did the neuroretinal rim.

Repeatability and reproducibility of anterior chamber angle measurement with anterior segment optical coherence tomography

AIM

To evaluate the repeatability and reproducibility of anterior chamber angle measurement obtained by anterior segment optical coherence tomography.

METHODS

Twenty-five normal subjects were invited for anterior chamber angle imaging with an anterior segment optical coherence tomography (OCT) on one randomly selected eye in three separate visits within a week. Each eye was imaged three times under room light (light intensity = 368 lux) and three times in the dark during the first visit. In the subsequent visits, each eye was imaged once in the light and once in the dark. The angle opening distance (AOD 500) and the trabecular-iris angle (TIA 500) were measured by a single observer. Only the nasal angle was analysed. Intrasession and intersession within-subject standard deviation (Sw), precision (1.96xSw), coefficient of variation (CVw) (100xSw/overall mean), and intraclass correlation coefficient (ICC) were calculated to evaluate repeatability and reproducibility.

RESULTS

For intrasession repeatability, the Sw, precision, CVw and ICC of AOD/TIA were 45 microm/2.4 degrees , 88 microm/4.7 degrees , 5.8%/4.8% and 0.97/0.95 in the light; and 45 microm/2.1 degrees , 88 microm/4.2 degrees , 7.0%/5.0% and 0.98/0.97 in the dark. For intersession reproducibility, the Sw, precision, CVw and ICC of AOD/TIA were 79 microm/3.5 degrees , 155 microm/6.8 degrees , 10.0%/7.0%, 0.91/0.89 in the light; and 64 microm/3.4 degrees , 124 microm/6.6 degrees , 9.9%/7.8% and 0.95/0.92 in the dark.

CONCLUSIONS

The anterior segment OCT demonstrated reliable anterior chamber angle measurement in different lighting conditions with good repeatability and reproducibility.

Perilimbal conjunctival pigmentation in Chinese patients with vernal keratoconjunctivitis

PURPOSE

To document the disease spectrum and evaluate the presence of perilimbal conjunctival pigmentation in Chinese patients with vernal keratoconjunctivitis (VKC).

METHOD

A case-control study was conducted between November 2004 and July 2005. Patients aged 18 or younger with VKC and age-matched children attending our eye clinic for refractive or orthoptic problems were recruited and compared. Detailed slit-lamp examination was performed noting in particular the presence of perilimbal conjunctival pigmentation, the severity of papillary reaction, and corneal complications of VKC.

RESULTS

A total of 19 patients and 23 controls were evaluated. The presence of bilateral large tarsal or limbal papillae and epithelial defect were significantly associated with symptoms severity (Fisher's exact test, P=0.015 and P=0.035 respectively). All VKC patients were found to have perilimbal conjunctival pigmentation in at least one eye. There was a significant correlation in the colour and density of pigments between the two eyes (Sperman's rho=0.93, P<0.001). None of the controls was found to have such perilimbal conjunctival pigmentation (Fisher's exact test, P<0.001).

CONCLUSION

The presence of perilimbal conjunctival pigmentation appears to be a consistent clinical finding in Chinese patients with VKC and may be a useful diagnostic sign for patients with subtle signs or symptoms.

Measuring triamcinolone acetonide in aqueous humor by gas chromatography-electron-capture negative-ion mass spectrometry

Intravitreal triamcinolone acetonide (IVTA) injection has been used in the treatment of various posterior segment diseases. One of the side effects of IVTA is raised intraocular pressure, which may be secondary to triamcinolone acetonide (TAA)'s effects on the trabecular meshwork that affects aqueous outflow. In order to study the biological effects of TAA on the trabecular meshwork, we firstly need to reliably and accurately detect the concentration of TAA in tissue cells or fluids. In this study we have described a technique of using gas chromatography-electron-capture-negative-ion mass spectrometry (GC-NCI-MS) to develop a simple, sensitive, selective and validated method to detect TAA in aqueous humor (AH) of rabbits following IVTA and subconjunctival TAA injections. We derivatized TAA from extracted aqueous sample by acetic anhydride and BSTFA, respectively, and analyzed by GC-NCI-MS. The detection limit was 0.3ng/ml, linearity over 0.995 from 0 to 300ng/ml. The reproducibility ranged from 10.4 to 3.9 for concentrations from 3 to 300ng/ml, and recovery was over 95% for the concentrations 10, 60, and 200ng/ml. No interference was found from 159 aqueous samples. There was no TAA residue carried to the next injection from previously high concentration injection, 10,000ng/ml. We have provided an alternative, rapid, and robust method other than LC-MS-MS for TAA detection in AH.

Regional variations in the relationship between macular thickness measurements and myopia

PURPOSE

To investigate the relationship between myopia and macular thickness, as measured by optical coherence tomography.

METHODS

A total of 143 normal subjects comprising 80 eyes with high myopia (spherical equivalent [SE] < -6.0 D), 37 eyes with low to moderate myopia (SE between -6.0 and -0.5 D), and 26 nonmyopic eyes (SE > -0.5 D) were analyzed in this cross-sectional study. Total average, foveal, and inner and outer average macular thicknesses measured by the StratusOCT (Carl Zeiss Meditec Inc., Dublin, CA) were compared among the three diagnostic groups. Associations between macular thickness and refractive error/axial length were evaluated by linear regression analysis.

RESULTS

The minimum foveal and average foveal (1-mm ring on the OCT retinal thickness map) thicknesses were significantly greater, and the outer ring macular (3-6-mm) thicknesses significantly lower in the high myopic eyes than in the low to moderate myopic and nonmyopic eyes. No significant difference was found in the inner ring (1-3-mm) macular thickness measurements among the groups. There was a positive correlation between the axial length and the average foveal thickness (r = 0.374, P < 0.001). Negative correlations were found between axial length and the average outer ring macular thickness (r= -0.471, P < 0.001) and total average macular thickness (r= -0.311, P < 0.001).

CONCLUSIONS

Retinal thickness is related to refractive error/axial length in normal subjects with regional variations in correlation within the 6-mm macular region. Analysis of macular thickness in the evaluation of macular diseases and glaucoma should be interpreted only in the context of refractive errors and the location of measurement.

Retinal nerve fiber layer measurements in myopia: An optical coherence tomography study

PURPOSE

To evaluate the relationship between retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and the axial length/refractive error of the eye.

METHODS

A total of 115 eyes of 115 healthy subjects, comprising 75 eyes with high myopia (spherical equivalent [SE] < -6.0 D) and 40 eyes with low to moderate myopia (SE between -6.0 D and -0.5D), were analyzed in this cross-sectional study. Total average and mean clock hour RNFL thicknesses were measured by OCT and compared between the two myopia groups. Associations between RNFL measurements and axial length and spherical equivalent were evaluated by linear regression analysis.

RESULTS

The RNFL measurements were significantly lower in the high myopia group compared with those of the low-to-moderate myopia group at 12, 1, and 7 o'clock (right eye orientation). Apart from the temporal clock hours, significant correlations were evident between RNFL measurements and the axial length and spherical equivalent. The average RNFL thickness decreased with increasing axial length (r = -0.314, P = 0.001) and negative refractive power (r = 0.291, P = 0.002). A significant proportion of myopic eyes were classified as outside normal limits, with reference to the normative database. The most frequently abnormal sector was at 2 o'clock, where 16.5% of myopic eyes were outside normal limits.

CONCLUSIONS

RNFL measurements vary with the axial length/refractive error of the eye. Analysis of RNFL thickness in the evaluation of glaucoma should always be interpreted with reference to the refractive status. Although the normative database provided by OCT has been helpful in identifying ocular diseases involving the RNFL, it may not be reliable in the analysis of myopic eyes.

A novel missense RP1 mutation in retinitis pigmentosa

AIMS

More than 20 mutations associated with retinitis pigmentosa (RP) have been identified in the retinitis pigmentosa 1 (RP1) gene, all of them leading to the production of a truncated protein without 50-70% of the C-terminal of the RP1 protein. RP1 was recently found to be a microtubule-associated protein (MAP) and responsible for the organisation of the photoreceptor outer segment. The N-terminal doublecortin (DCX) domain of RP1 is essential for its function. But how the C-terminal of the protein affects its function is still not known. This study aims to get a better understanding of the RP1 gene by mutation screening on RP patients.

METHODS

Peripheral blood was taken from 72 RP patients. Together with 101 RP patients and 190 control subjects previously reported, mutation screening was performed by polymerase chain reaction (PCR) and direct sequencing. Statistical analysis was performed using SPSS.

RESULTS

Two novel missense sequence changes, D984G and C727W, and one novel variant, 6492T>G, at the 3' untranslated region were found. They were not found in 190 control subjects. D984G causes RP. It creates two possible N-myristoylation sites according to PROSITE. C727W does not segregate with RP in the family. It abolishes an N-myristoylation site. R872H, a previously reported polymorphism, was predominantly present in control subjects (P=0.001).

CONCLUSIONS

Our results suggest that disruption of the C-terminal of RP1 may be associated with the development of RP, and the possible involvement of the RP1 polypeptide downstream of its DCX domain in normal RP1 function.

Precautions in ophthalmic practice in a hospital with a major acute SARS outbreak: an experience from Hong Kong

Many new infectious diseases in humans have been derived from animal sources in the past 20 years. Some are highly contagious and fatal. Vaccination may not be available and antiviral drugs are not effective enough. Infectious control is important in clinical medicine and in Ophthalmology. Severe acute respiratory syndrome (SARS), as an example, is a highly contagious respiratory disease that has recently been reported in Asia, North America, and Europe. Within a matter of weeks, the outbreak has evolved to become a global health threat and more than 30 countries have been afflicted with a novel Coronavirus strain (SARS-CoV) that is the aetiologic agent of SARS. The primary route of transmission of SARS appears involving close person-to-person contact through droplets. Ophthalmologists may be particularly susceptible to the infection as routine ophthalmic examinations like direct ophthalmoscopy and slit-lamp examination are usually performed in a setting that has close doctor-patient contact. Being the Ophthalmology Department of the only hospital in the world that has just gone through the largest outbreak of SARS, we would like to share our strategy, measures, and experiences of preventing contracting or spreading of SARS infection as an infection control model. SARS is one of the many viruses against which personnel will need protecting in an ophthalmic setting. The experiences attained and the measures established might also apply to other infectious conditions spreading by droplets such as the avian influenza with H5N1.