Late onset cone dystrophy

Intercalary membrane break and detachment causes intrachoroidal cavitation in macular coloboma

PURPOSE

To describe the clinical and imaging features in a series of patients diagnosed with macular coloboma (MC) and intrachoroidal cavitation (ICC).

METHODS

Patients diagnosed with MC based on clinical examination between June 2017 and July 2021 were retrieved from the electronic medical record system and were included in the study. Colour fundus photographs, optical coherence tomography (OCT) and Multicolour® imaging scans of these patients were analysed.

RESULTS

We identified 16 eyes of 11 patients with MC on fundus examination. Based on OCT imaging features, conforming variant of MC was seen in 9 (56%) eyes and non-conforming variant in 7 (44%) eyes. No eyes with MC in the study showed features of both conforming and non-conforming varieties simultaneously. In the non-conforming variety of MC with presence of intercalary membrane break, ICC was identified in 5 (71%) of these eyes. ICC in MC appeared as flat, dark greenish areas with or without an orange-coloured boundary abutting the margin of the coloboma on Multicolour® imaging.

CONCLUSION

In 31% eyes, ICC was seen in non-conforming type of MC and was well-identified on Multicolour® imaging. It appears that presence of intercalary membrane break and detachment are prerequisites for developing ICC.

A Systematic Review of the Clinical Manifestations and Diagnostic Methods for Macular Coloboma

Objectives: To present the clinical features of and diagnostic methods used for macular coloboma (MC), and to analyze the factors associated with best-corrected visual acuity (BCVA) in patients with MC.Methods: A systematic review using the MEDLINE (PubMed), EMBASE, LILACS, and Cochrane databases was performed. The factors associated with BCVA were analyzed.Results: A total of 21 patients (mean age at diagnosis, 18.1 ± 14.6 years) with 36 eyes affected by MC (5 unilateral, 16 bilateral) were included in the study. All 21 patients (100%) had undergone a good-quality fundus examination. The size of the MC lesions ranged from 1.0 × 1.2 to 4.0 × 4.0 disc diameters (DD). Twenty-seven (73%) eyes had pigmented MC, seven (19%) had non-pigmented MC, and one (3%) had an unspecific type. The diagnosis was confirmed using spectral-domain optical coherence tomography (SD-OCT) in 16 (43.2%) eyes. A positive correlation was found between BCVA and the type of MC (β = 0.876, p = .006) and abnormal eye movement (β = 0.087, p = .018), and a negative correlation was found between BCVA and a contributory medical history of ventricular septal defect (β = -0.327, p = .001).Conclusions: Pigmented MC was the most common type and had the highest possibility of causing impaired vision in the affected eyes. Additionally, joint examinations should be applied for diagnostic confirmation of MC. Furthermore, fundoscopy, electroretinogram, electrooculography, fundus fluorescein angiography, and SD-OCT are all critical for differential diagnosis of MC-like lesions.