Reproducibility of visual acuity measurements in patients with retinitis pigmentosa

RPE65 mutations in Leber congenital amaurosis, early-onset severe retinal dystrophy, and retinitis pigmentosa from a tertiary eye care center in India

INTRODUCTION

Mutations in the retinal pigment epithelial 65 kilodalton protein (RPE65) gene are associated with various inherited retinal diseases (IRDs), including Leber congenital amaurosis (LCA), early-onset severe retinal dystrophy (EOSRD), and retinitis pigmentosa (RP). We screened for mutations in RPE65 in a series of Indian patients with these IRDs to determine the frequency/types of mutations and to describe the associated phenotypes.

MATERIALS AND METHODS

Diagnosis of LCA, EOSRD, and RP was made by standard and pre-defined criteria. Patients were evaluated by clinical, retinal imaging, and electrophysiological parameters. Genomic DNA from patients and available family members were used for identifying mutations by direct Sanger sequencing of the RPE65 gene or targeted NGS gene panel for IRDs covering 260+ genes. Variations detected were tested in healthy control populations and for co-segregation with the disease in available family members.

RESULTS

Mutations were found in eight patients, out of 220 total cases screened, all homozygous for the respective mutant alleles. Seven patients had mutations leading to premature termination codons and one patient had a missense change. The onset of visual loss ranged from birth to <2 years of life. At presentation, RPE mottling in the background retina was present in all cases with macular involvement in five cases with or without vascular attenuation and optic disc pallor.

CONCLUSION

RPE65 mutations in this series were found in 3.6% of cases associated with severe, early-onset disease, with consistent RPE mottling and variable manifestations with regard to the extent of disc pallor, arteriolar attenuation, and appearance of the macula.

Loss of Foveal Cone Structure Precedes Loss of Visual Acuity in Patients With Rod-Cone Degeneration

Purpose

To assess the relationship between cone spacing and visual acuity in eyes with rod-cone degeneration (RCD) followed longitudinally.

Methods

High-resolution images of the retina were obtained using adaptive optics scanning laser ophthalmoscopy from 13 eyes of nine RCD patients and 13 eyes of eight healthy subjects at two sessions separated by 10 or more months (mean 765 days, range 311-1935 days). Cone spacing Z-score measured as close as possible (average <0.25°) to the preferred retinal locus was compared with visual acuity (letters read on the Early Treatment of Diabetic Retinopathy Study [ETDRS] chart and logMAR) and foveal sensitivity.

Results

Cone spacing was significantly correlated with ETDRS letters read (ρ = -0.47, 95%CI -0.67 to -0.24), logMAR (ρ = 0.46, 95%CI 0.24 to 0.66), and foveal sensitivity (ρ = -0.30, 95%CI -0.52 to -0.018). There was a small but significant increase in mean cone spacing Z-score during follow-up of +0.97 (95%CI 0.57 to 1.4) in RCD patients, but not in healthy eyes, and there was no significant change in any measure of visual acuity.

Conclusions

Cone spacing was correlated with visual acuity and foveal sensitivity. In RCD patients, cone spacing increased during follow-up, while visual acuity did not change significantly. Cone spacing Z-score may be a more sensitive measure of cone loss at the fovea than visual acuity in patients with RCD.

Relationship Between Foveal Cone Structure and Visual Acuity Measured With Adaptive Optics Scanning Laser Ophthalmoscopy in Retinal Degeneration

Purpose

To evaluate foveal function in patients with inherited retinal degenerations (IRD) by measuring visual acuity (VA) after correction of higher-order aberrations.

Methods

Adaptive optics scanning laser ophthalmoscopy (AOSLO) was used to image cones in 4 healthy subjects and 15 patients with IRD. The 840-nm scanning laser delivered an "E" optotype to measure AOSLO-mediated VA (AOSLO-VA). Cone spacing was measured at the preferred retinal locus by two independent graders and the percentage of cones below the average density of 47 age-similar healthy subjects was computed. Cone spacing was correlated with best-corrected VA measured with the Early Treatment of Diabetic Retinopathy Study protocol (ETDRS-VA), AOSLO-VA, and foveal sensitivity.

Results

ETDRS-VA significantly correlated with AOSLO-VA (ρ = 0.79, 95% confidence interval [CI] 0.5-0.9). Cone spacing correlated with AOSLO-VA (ρ = 0.54, 95% CI 0.02-0.7), and negatively correlated with ETDRS letters read (ρ = -0.64, 95% CI -0.8 to -0.2). AOSLO-VA remained ≥20/20 until cones decreased to 40.2% (CI 31.1-45.5) below normal. Similarly, ETDRS-VA remained ≥20/20 until cones were 42.0% (95% CI 36.5-46.1) below normal. Cone spacing z scores negatively correlated with foveal sensitivity (ρ = -0.79, 95% CI -0.9 to -0.4) and foveal sensitivity was ≥35 dB until cones were 43.1% (95% CI 39.3-46.6) below average.

Conclusions

VA and foveal cone spacing were weakly correlated until cones were reduced by 40% to 43% below normal. The relationship suggests that VA is an insensitive measure of foveal cone survival; cone spacing may be a more sensitive measure of cone loss.

Investigating the Usefulness of Fundus Autofluorescence in Retinitis Pigmentosa

PURPOSE

To investigate the relationship between visual field (VF) loss and the rings of the ellipsoid zone (EZ) and autofluorescence (AF) in patients with retinitis pigmentosa (RP).

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 28 eyes of 15 patients with a clinical diagnosis of RP.

METHODS

The VF was measured at a 1-degree interval on the horizontal or vertical lines, within the central 10 degrees from fixation, using MP-3 microperimetry (Nidek Co. Ltd., Aichi, Japan), and the sensitivity deviation from the normative database was calculated. OCT was performed, and the EZ was identified. Fundus AF was also measured, and the AF ring was identified. The VF test points were categorized according to their relationship with the EZ line and AF ring. The relationship between mean retinal sensitivity deviations on both the horizontal and vertical lines and the diameters of the EZ line and the AF ring in the corresponding directions was analyzed. The relationship between visual sensitivity deviation and the locations against EZ line and AF rings was also investigated.

MAIN OUTCOME MEASURES

The relationship between the visual sensitivity deviation and the locations against EZ line and AF rings.

RESULTS

The diameter of the AF ring had a significantly stronger relationship with mean retinal sensitivity deviation compared with the diameter of the EZ line in both the horizontal and vertical directions. Test point location inside/on/outside the AF ring was significantly related to retinal sensitivity deviation independent of the location inside/outside the EZ line (P < 0.001, linear mixed model).

CONCLUSIONS

Visual sensitivity damage is significantly associated with the EZ lines and AF rings. The development of the AF ring is related to the decrease of visual function independent of and stronger than the EZ line.

Test-Retest Variability of Functional and Structural Parameters in Patients with Stargardt Disease Participating in the SAR422459 Gene Therapy Trial

Purpose

The goal of this analysis was to determine the test–retest variability of functional and structural measures from a cohort of patients with advanced forms of Stargardt Disease (STGD) participating in the SAR422459 (NCT01367444) gene therapy clinical trial.

Methods

Twenty-two participants, aged 24 to 66, diagnosed with advanced forms of STGD, with at least one pathogenic ABCA4 mutation on each chromosome participating in the SAR422459 (NCT01367444) gene therapy clinical trial, were screened over three visits within 3 weeks or less. Functional visual evaluations included: best-corrected visual acuity (BCVA) Early Treatment Diabetic Retinopathy Study (ETDRS) letter score, semiautomated kinetic perimetry (SKP) using isopters I4e, III4e, and V4e, hill of vision (HOV) calculated from static visual fields (SVF) by using a 184n point centrally condensed grid with the stimulus size V test target. Retinal structural changes such as central macular thickness and macular volume were assessed by spectral-domain optical coherence tomography (SD-OCT). Repeatability coefficients (RC) and 95% confidential intervals (CI) were calculated for each parameter using a hierarchical mixed-effects model and bootstrapping.

Results

Criteria for statistically significant changes for various parameters were found to be the following: BCVA letter score (8 letters), SKP isopters I4e, III4e, and V4e (3478.85; 2488.02 and 2622.46 deg², respectively), SVF full volume HOV (V_TOT, 14.62 dB-sr), central macular thickness, and macular volume (4.27 μm and 0.15 mm³, respectively).

Conclusions

This analysis provides important information necessary to determine if significant changes are occurring in structural and functional assessments commonly used to measure disease progression in this cohort of patients with STGD. Moreover, this information is useful for future trials assessing safety and efficacy of treatments in STGD.

Translational Relevance

Determination of variability of functional and structural measures in participants with advanced stages of the STGD is necessary to assess efficacy and safety in treatment trials involving STGD patients.

Comparison of topical dorzolamide and ketorolac treatment for cystoid macular edema in retinitis pigmentosa and Usher's syndrome

PURPOSE

To investigate the topical effect of dorzolamide versus ketorolac on retinitis pigmentosa (RP) and Usher's syndrome (US) macular edema.

METHODS

Prospective, randomized and interventional study. A total of 28 eyes of 18 patients were included. Five eyes had US, 23 had RP. Fifteen eyes were allocated to ketorolac tromethamine 0.5% (4 drops daily regimen) and 13 eyes to dorzolamide hydrochloride 2% (3 drops daily regimen) treatment groups. Snellen's best-corrected visual acuity (BCVA), foveal thickness (FT) and foveal zone thickness (FZT) measured by Stratus® optical coherence tomography (OCT) were evaluated at baseline, 1, 3, 6 and 12 months after treatment.

RESULTS

Patients assigned to ketorolac had a baseline BCVA of 0.37 ± 0.17 logMAR which improved at the end of 1 year to 0.28 ± 0.16 (p = 0.02). Three eyes (20%) of 2 patients improved by 7 letters or more. Mean FT and FZT did not change significantly during the study follow-up. After 1 year of treatment, 4 eyes (27%) of 3 patients showed an improvement of at least 16% of FT and 11% of FZT. Patients assigned to dorzolamide had a baseline BCVA of 0.48 ± 0.34 logMAR which improved in the first 6 months (0.40 ± 0.30; p = 0.01), with a decrease at 1 year (0.42 ± 0.27; p = 0.20). Seven eyes (54%) of 5 patients had an improvement of 7 letters or more. Mean FT and FZT did not change significantly either. After 1 year of treatment, 3 eyes (23%) of 2 patients showed an improvement of at least 16% on FT and 11% on FZT.

CONCLUSIONS

RESULTS suggest that dorzolamide and ketorolac might improve visual acuity and therefore be of interest in selected cases. No relationship between retinal thickness fluctuation and visual acuity was found. Sample size was a limitation to the study.

Test-Retest Intervisit Variability of Functional and Structural Parameters in X-Linked Retinoschisis

PURPOSE

To examine the variability of four outcome measures that could be used to address safety and efficacy in therapeutic trials with X-linked juvenile retinoschisis.

METHODS

Seven men with confirmed mutations in the RS1 gene were evaluated over four visits spanning 6 months. Assessments included visual acuity, full-field electroretinograms (ERG), microperimetric macular sensitivity, and retinal thickness measured by optical coherence tomography (OCT). Eyes were separated into Better or Worse Eye groups based on acuity at baseline. Repeatability coefficients were calculated for each parameter and jackknife resampling used to derive 95% confidence intervals (CIs).

RESULTS

The threshold for statistically significant change in visual acuity ranged from three to eight letters. For ERG a-wave, an amplitude reduction greater than 56% would be considered significant. For other parameters, variabilities were lower in the Worse Eye group, likely a result of floor effects due to collapse of the schisis pockets and/or retinal atrophy. The criteria for significant change (Better/Worse Eye) for three important parameters were: ERG b/a-wave ratio (0.44/0.23), point wise sensitivity (10.4/7.0 dB), and central retinal thickness (31%/18%).

CONCLUSIONS

The 95% CI range for visual acuity, ERG, retinal sensitivity, and central retinal thickness relative to baseline are described for this cohort of participants with X-linked juvenile retinoschisis (XLRS).

TRANSLATIONAL RELEVANCE

A quantitative understanding of the variability of outcome measures is vital to establishing the safety and efficacy limits for therapeutic trials of XLRS patients.

Miscoded Visual Processing in Degenerative Retinal Disorder?

Standard electrophysiological procedures for visual testing were applied to record the retinal and cortical electrophysiological responses to contrast stimulation from 35 subjects with unambiguously diagnosed retinitis pigmentosa and severe impairment of visual acuity and field. Stimuli (central 9° of visual field) were sinusoidal bars with spatial frequencies of 0.6–1.2 cycle/degree and 1.3–5.0 cycle/degree for the retinal (pattern-ERG) and cortical (pattern-VEP) responses, respectively; contrast was 80%; reversal at 2.13 Hz. Structured pattern-ERG above noise level was recorded from 29 subjects at 0.6 cycle/degree and from 24 subjects at 1.2 cycle/degree; latencies were increased and amplitude reduced. Pattern-VEP responses above noise level, with increased latencies and reduced amplitude, were observed in 92% of subjects with unilateral and in all subjects with bilateral retinal response. Both responses were phase-locked to stimulus. No correlation with the residual visual acuity or field was detected. The observation is consistent with evidence of the disease sparing the neuroretina and with unconscious visual processing and suggests miscoding of visual information processing.

Intravitreal and subtenon depot triamcinolone as treatment of retinitis pigmentosa associated cystoid macular edema

We present a case of retinitis pigmentosa (RP) related cystoid macular edema (CME) refractory to oral acetazolamide and topical ketorolac that was treated with intravitreal and subtenon depot triamcinolone. A 32-year-old male with RP presented with complaints of bilateral decrease in visual acuity. His best-corrected visual acuity (BCVA) was 20/50 in the right eye and 20/100 in the left eye. After being informed of the available treatment options, the patient received bilateral intravitreal injection triamcinolone. The patient's BCVA improved to 20/40 in the right eye and 20/50 in the left eye and the CME was resorbed. However, 5 months after the injection in the left eye and two months in the right eye, visual acuity decreased due to recurrence of CME. We performed a second intravitreal injection in the left eye with improvement of visual and anatomic results, but we observed a recurrence of CME. Afterwards, we treated the patient with subtenon depot triamcinolone in both eyes, with the result that there was no recurrence after 4 months in OD or after 3 months in OS. We conclude that intravitreal and subtenon depot triamcinolone appear to provide at least temporary benefit in refractory CME as regards the improvement of visual acuity.

Relationship between foveal cone structure and clinical measures of visual function in patients with inherited retinal degenerations

PURPOSE

To study the relationship between cone spacing and density and clinical measures of visual function near the fovea.

METHODS

High-resolution images of the photoreceptor mosaic were obtained with adaptive optics scanning laser ophthalmoscopy from 26 patients with inherited retinal degenerations. Cone spacing measures were made close to or at the foveal center (mean [SD] eccentricity, 0.02 [0.03] degree; maximum eccentricity, 0.13 degree) and were converted to Z-scores, fraction of cones, and percentage-of-cones-below-average compared with normal values for each location (based on 37 age-similar visually normal eyes). Z-scores and percentage of cones below average were compared with best-corrected visual acuity (VA) and foveal sensitivity.

RESULTS

Visual acuity was significantly correlated with cone spacing (Spearman rank correlation ρ = -0.60, P = 0.003) and was preserved (≥ 80 letters), despite cone density measures that were 52% below normal. Foveal sensitivity showed significant correlation with cone spacing (ρ = -0.47, P = 0.017) and remained normal (≥ 35 decibels), despite density measures that were approximately 52% to 62% below normal.

CONCLUSIONS

Cone density was reduced by up to 62% below normal at or near the fovea in eyes with VA and sensitivity that remained within normal limits. Despite a significant correlation with foveal cone spacing, VA and sensitivity are insensitive indicators of the integrity of the foveal cone mosaic. Direct, objective measures of cone structure may be more sensitive indicators of disease severity than VA or foveal sensitivity in eyes with inherited retinal degenerations.

Phenotypic expression of Bardet-Biedl syndrome in patients homozygous for the common M390R mutation in the BBS1 gene

PURPOSE

To characterize the phenotype of Bardet-Biedl syndrome (BBS) patients homozygous for the BBS1 M390R mutation.

METHODS

Three patients [PT1, F, 27 years old (yo) at last examination, 14-year follow-up (F/U) PT2, F, 15-yo PT3, M, 15-yo, both 1-year F/U] underwent eye exams, Goldmann visual fields (GVFs), dark- (DA) and light-adapted (LA) electroretinograms (ERGs), spectral domain optical coherence tomography (SD-OCT) and fundus autofluorescence (FAF). Vision and systemic history were also collected.

RESULTS

All patients had night blindness, hyperopic astigmatism, ptosis or mild blepharospasm, foot polydactyly, 5th finger clinodactyly, history of headaches, and variable, diet-responsive obesity. Two had asthma, PT1 was developmentally delayed, PT2 had Asperger-like symptoms, and PT3 had normal cognition. At age 14, acuity was 20/100 in PT1, who had nystagmus since age 2, 20/40 in PT2 and 20/30 in PT3. By 27yo PT1 progressed to 20/320, by 15 yo PT2 was 20/60 and PT3 remained stable. PT1 had well preserved peripheral GVFs, with minimal progression over 10 years of F/U. PT2 and PT3 presented with ring scotomas and I4e<5°. All patients had severe generalized visual sensitivity depression. ERGs were consistently recordable (also rod ERG in PT3 after 60 min DA), but progressed to non-recordable in PT1. Mixed DA ERGs exhibited electronegativity. In PT3, this was partly due to a bleaching effect during bright-flash DA averaging, partly to ON≫OFF LA response compromise. PT2 and 3 had, on SD-OCTs, generalized macular thinning, normal retinal lamination, and widespread photoreceptor outer/inner segment attenuation except foveally, and multiple rings of abnormal FAF configuring a complex bull's eye-pattern. PT1 had macular atrophy. All patients also had peripapillary nerve fiber layer thickening.

CONCLUSIONS

The observed phenotype matches very closely that reported in patients by Azari et al. (IOVS 2006) and in the Bbs1-M390R knock-in mouse model, and expands it to the characterization of important ERG response characteristics that provide insight in the pathogenesis of retinopathy in these patients. Our findings confirm the consistent pathogenicity of the BBS1 M390R mutation.

Vision test variability in retinitis pigmentosa and psychosocial factors

PURPOSE

We explored whether greater amounts of short-term variability in visual acuity (VA), contrast sensitivity (CS), or visual field (VF) in retinitis pigmentosa (RP) was related to disease severity or psychosocial factors.

METHODS

We obtained spectral domain-optical coherence tomography in 27 RP subjects and determined variability (SD) of VA, CS, and VF during a mean of 16 tests self-administered at home on a personal computer twice a week. Subjects completed the Positive and Negative Affect Schedules at each personal computer-test session, and SF-36 general health and Beck Depression Inventory questionnaires on one occasion.

RESULTS

There was a 0.10 log unit increase in VA variability for every 0.58 logMAR increase (worse mean VA) (p = 0.001). For subjects with reduced foveal thickness, mean VA explained more of the total VA variability than foveal thickness (R² = 0.72 and 0.46, respectively, in simple linear regressions). There was a statistically significant 4.3% increased log VF area variability for every 50% mean log VF area decrease (p < 0.001); explaining most of the total variability in log VF area variability (R² = 0.44). When controlling for mean log VF area, there was a statistically significant increase in log VF area variability for subjects with greater than minimal depressive symptoms (p = 0.015), with increased mean irritability scores (p = 0.02), decreased SF-36 physical functioning subscale scores (p = 0.03), or decreased mean score for feeling active, strong, and proud (p = 0.008) (adjusted R² = 0.62). CS variability was low and not statistically significantly related to mean CS, macular thickness, or psychosocial factors.

CONCLUSIONS

Increased VA and VF variability was predicted largely by increased RP severity. Greater VF variability occurred in subjects with reduced VF who reported less physical activity or increased negative psychosocial states. These associations should be considered during clinical examinations and trials for RP.

X-linked retinoschisis maculopathy treated with topical dorzolamide, and relationship to genotype

PURPOSE

To correlate the response of topical dorzolamide (Trusopt; Merck) in patients with X-linked retinoschisis (XLRS) with genotype.

METHODS

We carried out a retrospective evaluation of four patients (seven eyes) with XLRS, treated with topical dorzolamide. The change in best-corrected visual acuity (VA) and central macular thickness (CMT; central 1 mm subfield thickness) from optical coherence tomography (OCT) was analysed over the follow-up period, using Student's t-test. Each patient also had genetic analysis for mutations in the retinoschisisgene (RS1).

RESULTS

The mean age at the start of treatment was 14.7±11 years, and mean follow-up duration was 21.7±7.7 months. Mean CMT at the final follow-up was significantly better than at baseline (291±123 vs 352±119 μm, P=0.007); however, mean VA was worse (0.38±0.25 vs 0.31±0.24 logMAR score, P=0.041). All four patients had a mutation in the RS1gene; there was no apparent association between the type of mutation and the response to topical dorzolamide.

CONCLUSION

Topical dorzolamide may have some effect in reducing central macular thickness in patients with XLRS, but this does not necessarily correlate with improvement in VA. In our case series, genotypic information did not predict the response to this treatment.

The use of carbonic anhydrase inhibitors in the retreatment of cystic macular lesions in retinitis pigmentosa and X-linked retinoschisis

PURPOSE

The purpose of this study was to determine if carbonic anhydrase inhibitors can restore their efficacy after a period of discontinued use in patients with cystic foveal lesions who demonstrated subsequent worsening in the extent of their foveal cysts after initially exhibiting a favorable response to treatment.

METHODS

Retrospective chart review was conducted on all patients with retinitis pigmentosa or X-linked retinoschisis who were either currently on treatment or had been treated with carbonic anhydrase inhibitors for cystic macular lesions. A total of three patients were included in the study.

RESULTS

All three patients exhibited a recurrence of their cystic macular lesions while on treatment with carbonic anhydrase inhibitors. After discontinuing treatment for a period of 1 month to 6 months, all patients showed a favorable response to retreatment as monitored with optical coherence tomography scans.

CONCLUSION

The present study shows that patients who show signs of recurring macular cysts while still on treatment can have a favorable response when treatment is reinstated after a period of discontinued use of a carbonic anhydrase inhibitor.

Efficacy of sustained topical dorzolamide therapy for cystic macular lesions in patients with retinitis pigmentosa and usher syndrome

OBJECTIVE

To determine the efficacy of sustained topical therapy with dorzolamide hydrochloride, 2%, on visual acuity and cystic macular lesions in patients with retinitis pigmentosa and Usher syndrome.

METHODS

In a retrospective case series at a university hospital, 64 eyes of 32 patients with retinitis pigmentosa or Usher syndrome receiving treatment with the topical dorzolamide formulation for 6 to 58 months were enrolled. Changes in visual acuity on the Early Treatment Diabetic Retinopathy Study chart and central foveal zone thickness on optical coherence tomography were measured during follow-up for the duration of treatment.

RESULTS

Among the study cohort, 20 of 32 patients (63%) showed a positive response to treatment in at least 1 eye and 13 patients (41%) showed a positive response in both eyes. Four patients (20%) showed an initial response and a subsequent rebound of macular cysts. In 8 patients (25%), there was no response to treatment and the macular cysts worsened when compared with the pretreatment level. Ten patients (31%) had improvement in visual acuity by 7 or more letters in at least 1 eye at the most recent follow-up visit. Sixteen patients (67%) showed a reduction of more than 11% in the central foveal zone thickness in at least 1 eye when compared with the pretreatment level.

CONCLUSIONS

Patients with either retinitis pigmentosa or Usher syndrome who received treatment of cystoid macular edema with topical dorzolamide followed by an optical coherence tomography-guided strategy showed a decrease in central foveal zone thickness in most cases. Visual acuity improved in almost one-third of the cases, suggesting a potential corresponding visual benefit.

Continued use of dorzolamide for the treatment of cystoid macular oedema in patients with retinitis pigmentosa

AIM

To determine the value of a topical carbonic anhydrase inhibitor for extended treatment of cystoid macular oedema (CME) in patients with retinitis pigmentosa (RP).

METHOD

Eight patients with RP and foveal cystic-appearing lesions observed on fundus examination and by optical coherence tomography (OCT) testing were treated with a topical form of carbonic anhydrase inhibitor.

RESULTS

Foveal cystic-like spaces were documented by OCT testing in all eight patients before treatment. All patients had a significant reduction in their foveal thickness (FT) and foveal zone thickness (FZT) in at least one eye after using 2% dorzolamide three times a day for 1 or 2 months. Six patients had an improvement in both eyes. After an additional 6-13 months of the same treatment regimen, out of six patients who had a sustained reduction in FT and FZT in at least one eye, four had this reduction in both eyes. While they were still taking Trusopt, a recurrence (rebound) of CME in both eyes was observed in two patients, whereas one patient had a sustained improvement in one eye and rebound of CME in the other eye. Out of 8 patients, 3 showed an improvement in their visual acuity by > or =7 letters, in at least one eye, on Snellen acuity charts, which was determined as clinically significant.

CONCLUSION

Results from this study suggest that patients with RP could potentially sustain a beneficial effect from continued treatment with a topical form of carbonic anhydrase inhibitor.

USE OF DORZOLAMIDE FOR PATIENTS WITH X-LINKED RETINOSCHISIS

PURPOSE

To determine the value of a topical carbonic anhydrase inhibitor for the treatment of foveal lesions in patients with X-linked retinoschisis (XLRS).

METHODS

Eight patients with XLRS and foveal cystic-appearing spaces by fundus examination and by optical coherence tomography (OCT) were treated with a topical form of carbonic anhydrase inhibitor. Changes in "foveal thickness" and "foveal zone thickness" were measured by OCT, and changes of best-corrected visual acuity were measured by Early Treatment Diabetic Retinopathy Study (ETDRS) charts.

RESULTS

Seven of eight patients treated with 2% dorzolamide had a noticeable reduction in foveal thickness as well as cystic-appearing spaces by OCT. This reduction was found in both eyes in four of these patients and in one eye in one patient after 1 month of treatment. After an additional 1 month to 2 months of the same treatment regimen, two additional patients also had a noticeable reduction in foveal thickness as well as cystic-appearing spaces. Of these seven patients who had an improvement shown by OCT with treatment, five also had improvement of their visual acuity by >or=7 letters in at least one eye on ETDRS charts.

CONCLUSION

The present study shows the efficacy of topical dorzolamide for treating foveal cystic-appearing lesions in patients with XLRS.

Topical dorzolamide for the treatment of cystoid macular edema in patients with retinitis pigmentosa

PURPOSE

To determine if topical dorzolamide, as observed with the use of systemic acetazolamide and methazolamide, would be effective in treating cystoid macular edema (CME) in patients with retinitis pigmentosa (RP).

DESIGN

Prospective, nonrandomized clinical trial.

METHODS

setting: Institutional. patients: Fifteen patients with CME and RP. intervention: A baseline visual acuity and optical coherence tomography (OCT) measurements were obtained in all patients. Each one of them was then treated with topical dorzolamide, three times a day, for at least four weeks in both eyes. main outcome measures: Significant decrease in "foveal thickness" (more than 16%) and "foveal zone thickness" (more than 11%), as measured by OCT.

RESULTS

Thirteen (87%) of 15 patients showed a significant decrease in retinal thickness in at least one eye after use of topical dorzolamide for at least four weeks. Five patients (33%) demonstrated improvement in both eyes. All patients, except one, who responded showed the effect within four weeks, but were monitored for a period of two to nine months (average 4.5 months). Four patients (31%) who showed an initial improvement in macular edema showed worsening with continued treatment.

CONCLUSIONS

The present study documents the potential efficacy of topical dorzolamide for treating CME in patients with RP. We observed that some patients may show a "rebound phenomenon" with continued use of the medication; hence, there is a need for careful follow-up in patients being treated.

Retinitis pigmentosa: visual function and multidisciplinary management

Retinitis pigmentosa (RP) is a leading cause of blindness and visual disability in younger people. Optometrists have a major role in detecting RP and in reducing the visual disability associated with RP. This review summarises the literature relating to visual function in people with RP, with particular attention given to night-blindness, visual acuity decrease and visual field contraction. The range of low vision aids available for people with RP is reviewed and suggestions given on aids that have been found to be most successful. Most importantly, this review overviews the range of services available to people with RP and emphasises how optometrists need to work with a network of professionals to ensure the best possible visual outcomes for people with RP. Particular mention is made of current findings relating to orientation and mobility training, driving, sensory substitution and adaptive technology. The modern optometrist needs to be aware of the multiple needs of people with RP and have the ability to link them with the professionals best able to help them.

Retrospective, longitudinal, and cross sectional study of visual acuity impairment in choroideraemia

BACKGROUND/AIMS

Few studies have reported on the change in visual acuity (VA) in patients with choroideraemia. In order to determine the degree and rate of VA impairment associated with this disease, the central VA was analysed in a large group of patients with choroideraemia.

METHODS

The authors completed a retrospective, cross sectional review of 115 patients with choroideraemia from three tertiary care centres. A longitudinal analysis was performed on 45 of these patients who met the inclusion criteria of at least three visits over a minimum period of 4.5 years. Multiple linear regression analysis was used to explore the 5 year rate of VA change while controlling for initial VA and initial age. Multiple logistic regression was also used to investigate VA impairment.

RESULTS

In the cross sectional group (n = 115), 84% (87/103) of patients under the age of 60 had a VA of 20/40 or better while 33% (4/12) of patients 60 years of age or older had a VA of 20/200 or worse at their most recent visit. The majority of the patients (93%) in the longitudinal subgroup of 45 patients had a VA of 20/30 or better at their initial visit. The mean 5 year rate of VA change was 0.09 logMAR equivalent (approximately one line on the Lighthouse chart).

CONCLUSION

In this cohort of patients with choroideraemia, there was typically a slow rate of VA loss and the prognosis for central VA retention was, as a group, favourable until the seventh decade.

Retrospective longitudinal study of visual acuity change in patients with retinitis pigmentosa

PURPOSE

To determine the extent that clinically evident macular lesions in patients with retinitis pigmentosa (RP) help to establish their prognosis for visual acuity (VA) retention.

METHODS

The records of 182 patients with RP were reviewed. The macular lesion status at the initial examination was determined to be no lesion, a bull's-eye atrophic lesion, or a geographic atrophic lesion. Multiple linear regression analysis was used to evaluate the relationship of initial VA, macular lesion type, and RP genetic subtype to predict the VA change per 5-year period.

RESULTS

The regression effect of lesion type on the VA change was statistically significant (P < 0.0001). Patients with no macular lesion had a predicted 5-year change of less than 1 line, whereas those with either a bull's-eye or geographic atrophic lesion had a predicted 5-year change of three to four lines. The 5-year changes were not related to a patient's age or level of VA at initial presentation, when controlling for type of macular lesion.

CONCLUSION

By examining longitudinal data, the authors found that the presence or absence of a macular lesion at the patient's initial visit was an important determinant of VA loss in this cohort of patients with RP. These findings are of value when counseling patients with RP regarding their prognosis for preservation of VA.

A longitudinal study of visual function in carriers of X-linked recessive retinitis pigmentosa

OBJECTIVE

This study was carried out to evaluate the progression of visual function impairment in carriers of X-linked recessive retinitis pigmentosa. We also assessed the relationship between the retinal findings at presentation and the extent of deterioration.

DESIGN

Observational, retrospective, case series.

PARTICIPANTS

Twenty-seven carriers of X-linked recessive retinitis pigmentosa.

METHODS

Each carrier was clinically categorized into one of four grades (grades 0 through 3) depending on the presence or absence of a tapetal-like retinal reflex and the extent of peripheral pigmentary degeneration. A complete ophthalmologic examination was performed and data for visual acuity, visual field area, and electroretinographic measurements were collected on the most recent visit in both eyes. These were then compared with similar data obtained on their initial visits.

MAIN OUTCOME MEASURES

A comparison of visual function was carried out between the initial visit and the most recent visit on each carrier. The visual acuity was measured with Snellen's acuity charts. The visual fields to targets V-4-e and II-4-e were planimeterized and used for the analysis. The electroretinographic (ERG) measures used were light-adapted single-flash b-wave amplitudes and 30-Hz red flicker for cone function, dark-adapted maximal b-wave amplitudes, and response to a low intensity blue-flash for rod function.

RESULTS

None of the 11 carriers with a tapetal-like reflex only (grade 1) showed any significant change in visual acuity or fields as compared with 3 of 7 (43%) carriers with diffuse peripheral pigmentary findings (grade 3) who showed significant deterioration in visual acuity in at least one eye, and 6 of 7 (86%) who showed a significant decrease in visual field area with at least one target size in at least one eye. By comparison, only 1 of 10 carriers with a grade 1 fundus finding demonstrated a significant decrease in maximal dark-adapted ERG function as compared with 5 of 6 (83%) carriers with grade 3 in response to a single-flash stimulus and with 4 of 5 (80%) carriers in response to a single-flash blue stimulus. For the single-flash photopic response, none of the 10 carriers with grade 1 showed any significant deterioration, whereas 2 of 4 (50%) with grade 3 did show such deterioration. The ERG responses for carriers with grade 2 were in between the extent of decrease in ERG amplitudes of those in carriers with grades 1 and 3.

CONCLUSIONS

In our cohort of X-linked retinitis pigmentosa carriers, those with only a tapetal-like retinal reflex at presentation had a better prognosis to retain visual function than those with peripheral retinal pigmentation. These data are useful in counseling such carriers as to their visual prognosis.

The transplantation of human fetal neuroretinal cells in advanced retinitis pigmentosa patients: results of a long-term safety study

The purpose of this study was to determine the long-term safety of transplanting human fetal neuroretinal cells (14 to 18 week gestational age) into a series of patients with advanced retinitis pigmentosa (RP). After obtaining informed consent, both hosts and mothers of donors were screened for transmissible diseases. Pre- and postoperative clinical exams, visual acuity, electroretinograms, and fluorescein angiograms were performed and visual field testing was attempted in each case. Surgically, an anterior approach through pars plana ciliaris was used. A retinotomy was performed in the paramacular area and a two-function cannula was introduced into the subretinal space to deliver a suspension of donor cells. The cell suspension carried approximately 4000 cells/microl; the volume injected did not exceed 150 microl. The patients were examined for periods ranging from 12 to 40 months posttransplantation. To date, no evidence of inflammation, infection, or overt rejection of the graft was noted in the host eye, neither was any change observed in the contralateral, unoperated eye. In conclusion, neuroretinal cells were injected into the subretinal space of 14 patients with advanced RP with no clinical appearance of detrimental effects at the time of surgery or up to 40 months postinjection except in 1 patient who developed retinal detachment. This sets the stage for a phase II clinical trial to determine the possible beneficial effects of this procedure in patients blinded by degenerative retinal disease.