Unusual OCT findings in a patient with CABP4-associated cone-rod synaptic disorder.

PURPOSE: Bi-allelic variants in CABP4 are associated with congenital cone-rod synaptic disorder, which has also been classified, electrophysiologically, as incomplete congenital stationary night blindness (iCSNB). We describe clinical findings in a patient who demonstrated an unusual macular optical coherence tomography (OCT) phenotype, not previously reported in this condition. METHODS: Our patient underwent multimodal retinal imaging, international standard full-field ERG testing and whole genome sequencing. RESULTS: The patient was a 60-year-old woman with non-progressive visual impairment since birth, nystagmus and preference for dim lighting. Clinical fundus examination was unremarkable. OCT imaging revealed a hypo-reflective zone under an elevated fovea in both eyes. ERGs showed an electronegative DA10 response, with severely abnormal light-adapted responses. Whole genome sequencing revealed homozygosity for a known pathogenic variant in CABP4. No variants were found in other genes that could explain the patient's phenotype. CONCLUSIONS: OCT findings of foveal elevation and an underlying hypo-reflective zone are novel in this condition. Whilst the clinical history was similar to achromatopsia and other cone dysfunction syndromes, ERG findings suggested disease associated with CACNA1F or CABP4. As CACNA1F is X-linked, CABP4 was more likely, and confirmed on genetic testing. The patient saw better in dim light, confirming that night blindness is not a feature of CABP4-associated disease. Our case highlights the value of ERGs in discriminating between causes of cone dysfunction, and extends the range of retinal imaging phenotypes reported in this disorder.

Impact of cessation of regular cataract surgery during the COVID pandemic on the rates of posterior capsular rupture and post-operative cystoid macular oedema.

BACKGROUND/OBJECTIVES: During the COVID-19, elective cataract surgery (CS) was significantly curtailed. We investigated whether consequent reduction of micro-surgical skills practice might lead to higher operative complications. METHODS: Single-centre, electronic note review of consecutive patients undergoing CS during three periods: 1st February 2019 to 13th January 2020 (P1) prior to pandemic; 3rd June 2020 to 11th January 2021 after 1st lockdown (P2); and 25th January to 30th July 2021 (P3) after/during second lockdown. RESULTS: 2276 operations occurred during P1, 999 during P2, 846 during P3. During P1, posterior capsular rupture (PCR) rate was 1.67%, similar to P2 (1.30%, p = 0.54), but lower than P3 (3.55%, p = 0.002). There was no difference in PCR risk percentage scores between routine and PCR cases during P1 (1.90% vs 2.03%, p = 0.83), P2 (2% vs 2.18%, p = 0.18), or P3 (1.87% vs. 2.71%, p = 0.08). During P2 and P3, there was a higher rate of cystoid macular oedema (CMO) compared with P1 (4.9% and 6.86% vs. 1.93%, p = 0.0001), with no differences in proportion of diabetics or cases with CMO in combination with PCR. There was no difference in surgeons grade experiencing PCR. CONCLUSIONS: In P3 following 9 months of curtailed elective CS, PCR rates were increased across all surgeon grades, occurring in cases with similar risk percentage scores. CMO rates were increased during COVID and not related to proportion of diabetics or increased PCR rates. The reduction in elective CS during the pandemic was associated with more complications, perhaps due to attenuation of microsurgical skills.