Natural history and biomarkers of KCNV2-associated retinopathy.

BACKGROUND: KCNV2-associated retinopathy is an autosomal recessive inherited retinal disease classically named cone dystrophy with supernormal rod response (CDSRR). This study aims to identify the best biomarker for evaluating the condition. METHODS: A retrospective review of eight patients from seven families with genetically confirmed KCNV2-associated retinopathy was performed. The best corrected visual acuity (BCVA), full-field electroretinogram (ffERG), pattern ERG (pERG), fundus imaging: retinal photograph and fundus autofluorescence (FAF), and optical coherence tomography (OCT) were analysed. RESULTS: There was a disproportionate increase in b-wave amplitude with a relatively small light intensity increase, especially between the two dimmest stimuli of DA 0.002 and 0.01 (-2.7 and -2.0 log cd.s/m2). The a-wave amplitude was normal. The a-wave peak time was delayed in all stimuli. The b-wave peak time was delayed compared to normal, but the gap tightened as intensity increased. The b:a wave ratio was above or at the upper limit for the reference values. FAF bull's eye maculopathy pattern was prominent and variable foveal disruption on OCT was apparent in all patients. Legal blindness was reached before the age of 25. CONCLUSIONS: We identified three potential electrophysiology biomarkers to assist in evaluating future therapies: the disproportionate b-wave amplitude jump, delayed a-wave and b-wave peak time, and the higher than normal b:a wave ratio. Any of these biomarkers found with photoreceptor ellipsoid zone foveal-perifoveal disruption should prompt consideration for KCNV2 retinopathy. The BCVA natural history data suggests the probable optimum therapeutic window in the first three decades of life.

Electronegative electroretinogram in the modern multimodal imaging era.

BACKGROUND: The electronegative electroretinogram (ERG) reflecting inner retinal dysfunction can assist as a diagnostic tool to determine the anatomical location in eye disease. The aim of this study is to determine the frequency and aetiology of electronegative ERG in a tertiary ophthalmology centre and to develop a clinical algorithm to assist patient management. METHODS: Retrospective review of ERGs performed at the Save Sight Institute from January 2011 to December 2020. ERGs were performed according to ISCEV standard. The b:a ratio was analysed in dark adapted (DA) 3.0 or 12.0 recordings. Patients with ratio of ≤1.0 were included. RESULTS: A total of 4421 patients had ERGs performed during study period, of which 139 patients (3.1%) had electronegative ERG. The electronegative ERG patients' median age at referral time was 37 (0.7-90.6) years. The causative aetiologies were photoreceptor dystrophy (48, 34.5%), Congenital Stationary Night Blindness (CSNB) (33, 23.7%), retinal ischemia (18, 12.9%), retinoschisis (15, 10.8%), paraneoplastic autoimmune retinopathy (PAIR) and nonPAIR (14, 10.1%), batten disease (4, 2.9%), and inflammatory retinopathy (4, 2.9%). There were three patients with an unclassified diagnosis. Thirty-two patients (23%) had good vision and a normal fundus appearance. Eleven patients (7.9%) had good vision and normal results in all multimodal imaging. CONCLUSIONS: The frequency of electronegative ERG in our referral centre was 3.1% with photoreceptor dystrophy as the main aetiology. A significant number of the cases had good vision with normal fundus or normal multimodal imaging. This further highlights the value of an ERG in this modern multimodal imaging era.

Assessing Residual Cone Function in Retinitis Pigmentosa Patients.

Purpose: The purpose of this study was to investigate cone function deterioration in patients with retinitis pigmentosa (RP) using full field electroretinogram (ffERG), pattern electroretinogram (pERG), and optical coherence tomography (OCT) and their correlation with visual acuity (VA). Methods: Clinical records (2008-2018) of patients with RP undergoing repeat electrophysiology were reviewed. Results of ffERG (30 Hz flicker and fused flicker amplitude [FFAmp]), pERG [p50 and n95], and macular OCT (ellipsoid zone [EZ] and outer segment thickness) were collected. Results: One hundred twenty-six eyes from 63 patients (33 women, mean age 35 years) were included. The mean decline in VA was 0.11 ± 0.14 logarithm of minimum angle of resolution (logMAR). The FFAmp decreased by 3.01 ± 5.9 µV with global cone function deteriorating by 18.7% annually. The percentage change in FFAmp (RE [r = 0.553], LE [r = 0.531]), and 30 Hz flicker amplitude (RE [r = 0.615], LE [r = 0.529]) strongly correlated with VA (P < 0.00001). The pERG p50 (15 and 30 degrees) change analyzed in 34 patients showed reduction by 23% and 23.4%, respectively. The percentage change in p50 30 degrees (r = 0.397) correlated with VA and EZ layer (P < 0.05). The EZ layer change was calculated in 45 patients and the shortening and thinning rate was 4.3% and 4.4% annually, respectively. The EZ length percentage change correlated with VA (RE [r = 0.34] and LE [r = 0.466; P < 0.05). Conclusions: We quantified the decline in cone function in patients with RP utilizing ffERG and FFAmp measures of residual cone function. These parameters correlated with VA and OCT when measurable. These objective measures may assist in monitoring disease progression. Translational Relevance: Residual cone function provides an objective estimate of residual visual function, which aids in counselling patients regarding prognosis.

Five-year results of a randomized trial with open-label extension of triamcinolone acetonide for refractory diabetic macular edema.

OBJECTIVE: To report 5-year outcomes from a clinical trial of intravitreal triamcinolone acetonide (IVTA) in eyes with diabetic macular edema (DME) and impaired vision despite previous laser treatment. DESIGN: Prospective, double-masked, randomized clinical trial. After completing the 2-year visit, all eyes, including those initially randomized to receive placebo, received IVTA according to prospectively defined guidelines. PARTICIPANTS AND CONTROLS: A total of 69 eyes (41 patients) were entered into the study, with 34 eyes initially receiving active treatment and 35 eyes receiving placebo. Five-year data were available for 44 of 67 eyes (66%). For the 23 eyes with missing 5-year data, of which 13 received placebo and 10 received IVTA, the last observation was carried forward. INTERVENTION: Intravitreal injection of 0.1 ml of 40 mg/ml triamcinolone acetonide with adjunctive laser therapy where appropriate. MAIN OUTCOME MEASURES: Improvement of best-corrected logarithm of the minimum angle of resolution visual acuity by >or=5 letters after 5 years compared with baseline and 2 years, and incidence of adverse events. Secondary outcome was the change in central macular thickness. RESULTS: Improvement of >or=5 letters after 5 years was found in 14 of 33 eyes (42%) initially treated with IVTA compared with 11 of 34 eyes (32%) initially treated with placebo (z(GEE) = 0.81, P = 0.4). Foveal thickness decreased by 30 microm (95% confidence interval, -47 to 107 microm) less in the initial-IVTA group than in the initial-placebo group at 5 years (z(GEE) = 0.76, P = 0.45); 5 of 11 eyes (45%) from the initial-IVTA group that were phakic at commencement of the third year required cataract surgery. A similar number of eyes from each group required ongoing treatment from the third year onward with both laser and IVTA, indicating that IVTA treatment for 2 years does not lead to reduction in the risk of recurrent edema. CONCLUSIONS: The majority of eyes that initially improved with IVTA maintained their gain after 5 years. No new safety concerns were identified. IVTA treatment may be considered in carefully selected cases of impaired vision caused by advanced DME that are unresponsive to other interventions.

Familial asymptomatic macular telangiectasia type 2.

OBJECTIVE: To report findings in asymptomatic family members of patients with macular telangiectasia type 2. DESIGN: Prospective, observational, cross-sectional case series. PARTICIPANTS: Four patients with symptomatic macular telangiectasia type 2 (index patients) and 5 relatives, including 2 sets of monozygotic twins. METHODS: Screening of family members of participants in a non-interventional natural history study of macular telangiectasia type 2. Ophthalmologic examination included best-corrected visual acuity testing, fundus biomicroscopy, fluorescein angiography (FA), optical coherence tomography (OCT), and fundus autofluorescence (FAF) imaging. MAIN OUTCOME MEASURES: Evidence for macular telangiectasia type 2 in any of the imaging methods used and visual function of the family members studied. RESULTS: In the first family, 2 of 3 daughters of a severely affected 68-year-old woman had features of macular telangiectasia type 2. Although one of the daughters was diagnosed by biomicroscopic examination, the second daughter was diagnosed only by subtle changes on OCT and FAF imaging. Both affected daughters were asymptomatic and were unaware that they had the condition. In the second family, clinical examination showed that the 60-year-old brother of the 75-year-old index patient obviously was affected, despite a lack of any subjective visual dysfunction. The 65-year-old monozygotic twin of the third index patient showed a slight retinal thinning within a small area temporal to the foveola in both eyes as well as minor staining on FA and a subtle monocular loss of macular pigment. The 56-year-old asymptomatic monozygotic twin of the last proband had opacification of the retina with leakage on FA in the right eye. The fellow eye was unremarkable except for an abnormal FAF signal that was present in both eyes. CONCLUSIONS: Macular telangiectasia type 2 may be more common than previously assumed, but patients may not seek ophthalmic care if their visual function is normal. The study of these early, asymptomatic cases may yield valuable insights into the pathogenesis of the condition. Further research is warranted to determine whether there is an underlying, dominantly inherited genetic abnormality in macular telangiectasia type 2 of variable penetrance and expressivity.

Intravitreal triamcinolone for refractory diabetic macular edema: two-year results of a double-masked, placebo-controlled, randomized clinical trial.

OBJECTIVE: To report 2-year safety and efficacy outcomes from a trial of intravitreal triamcinolone acetonide (TA) injections (4 mg) in eyes with diabetic macular edema and impaired vision that persisted or recurred after laser treatment. DESIGN: Prospective, double-masked, placebo-controlled, randomized clinical trial. PARTICIPANTS AND CONTROLS: Sixty-nine eyes of 43 patients were entered into the study, with 34 eyes randomized to receive active treatment and 35 placebo. Two-year data were available for 60 of 69 (87%) eyes of 35 of 41 (85%) patients; 9 eyes of 6 patients were lost to follow-up, of which 6 received a placebo and 3 received intravitreal TA. INTERVENTION: Triamcinolone acetonide (0.1 ml) was injected through the pars plana using a 27-gauge needle. Eyes randomized to placebo received a subconjunctival injection of saline. MAIN OUTCOME MEASURES: Improvement of best-corrected logarithm of the minimum angle of resolution visual acuity (VA) by > or =5 letters after 2 years and incidence of moderate or severe adverse events. RESULTS: Improvement of > or =5 letters' best-corrected VA was found in 19 of 34 (56%) eyes treated with intravitreal TA, compared with 9 of 35 (26%) eyes treated with the placebo (z(generalized estimating equation) = 2.73, P = 0.006). The mean improvement in VA was 5.7 letters (95% confidence interval, 1.4-9.9) more in the intravitreal TA-treated eyes than in those treated with the placebo. An increase of intraocular pressure (IOP) of > or =5 mmHg was observed in 23 of 34 (68%) treated versus 3 of 30 (10%) untreated eyes (P<0.0001). Glaucoma medication was required in 15 of 34 (44%) treated versus 1 of 30 (3%) untreated eyes (P = 0.0002). Cataract surgery was performed in 15 of 28 (54%) treated versus 0 of 21 (0%) untreated eyes (P<0.0001). Two eyes in the intravitreal TA-treated group required trabeculectomy. There was one case of infectious endophthalmitis in the treatment group. CONCLUSION: Intravitreal TA improves vision and reduces macular thickness in eyes with refractory diabetic macular edema. This beneficial effect persists for up to 2 years with repeated treatment. Progression of cataract and elevation of IOP commonly occur but appear manageable. Spontaneous improvement over years can still occur in eyes that are apparently severely affected by diabetic macular edema.