Cupping of large optic discs - a diagnostic challenge in African patients

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Published Nov 29, 2024
DOI: https://doi.org/10.18103/mra.v12i11.6107

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Main Article Content

Dr. Darshana Soma, MBChB, FC Ophth(SA), MMed(Ophth)(SA)
Senior Lecturer and Clinical Unit Head of Ophthalmology at Steve Biko Academic Hospital, Division of Ophthalmology, Department of Health Sciences, University of Pretoria, Pretoria, South Africa.
Prof. GD McLaren, MBBCh, FCS(SA)Ophth, FRCOphth(UK)
Emeritus Professor, Division of Ophthalmology, Department of Neurosciences, University of Witwatersrand, Johannesburg, South Africa.
TR Carmichael, MBBCh(Wits), FC Ophth(SA), PhD(Med), MSc
Professor, Division of Ophthalmoogy, Department of Neurosciences, University of Witwatersrand, Johannesburg, South Africa. MBBCh(Wits), FC Ophth(SA), PhD(Med), MSc(med)

Abstract

Purpose: To determine in a cohort of 69 African patients with large optic discs and large optic cups, that proportion of patients with physiologic cupping (normal eyes) misdiagnosed as glaucomatous. To evaluate the possible relationship between optic disc size and central corneal thickness.


Method and design: A case series of 69 African patients with large optic discs (vertical disc height measuring >1.8mm) and large optic cups (vertical cup to disc ratio ≥0.6) was evaluated to determine what proportion had glaucoma and what proportion was normal. Patients categorized as normal were further evaluated to determine what proportion were previously misdiagnosed and treated for glaucoma. Patients with a suspected diagnosis of glaucoma, normal tension glaucoma or primary open angle glaucoma were recruited from the glaucoma clinic at St John Eye Hospital in South Africa.


Outcome measures included corrected vertical disc height, vertical cup to disc ratio, intraocular pressure, central corneal thickness, retinal nerve fibre layer analysis and visual fields.


Results: Sixty-nine African patients (138 eyes) with large optic discs and large optic cups were evaluated. 41 patients (59%) were females and 28 (41%) were males. The mean age was 56 years. Of the 69 patients, 51 (74%) had physiologic cupping (normal eyes) and 18 (26%) patients had glaucoma. Of the group of 51 patients with physiologic cupping, there were 9 patients who were previously misdiagnosed with glaucoma and who had received treatment.


Vertical disc height ranged between 1.9 and 3.2 mm (mean±SD, 2.3±0.26mm). The distribution analysis of the vertical disc height measurements noted the largest cluster around 2.3mm. The central corneal thickness ranged between 454µm and 618µm (mean±SD, 516±37um). 107 (77.5%) of the 138 eyes had central corneal thickness less than 544µm.


Conclusion: Large optic cup to disc ratio in relation to large disc size can be normal. It can be misdiagnosed as glaucomatous if objective retinal nerve fibre layer analysis is not carried out. In this study, 9(18%) patients from a group of 51 patients with physiologic cupping were misdiagnosed as glaucomatous. There was no linear correlation between central corneal thickness and vertical disc height in this study. Pearson's correlation coefficient was 0.13. The majority (77.5%) of eyes had thin corneas. Central corneal thickness less than or equal to 544µm.

Keywords: large optic discs, large optic cups, physiologic cupping, central corneal thickness, glaucoma, African

Article Details

How to Cite
SOMA, Dr. Darshana; MCLAREN, Prof. GD; CARMICHAEL, TR. Cupping of large optic discs - a diagnostic challenge in African patients. Medical Research Archives, [S.l.], v. 12, n. 11, nov. 2024. ISSN 2375-1924. Available at: <https://esmed.org/MRA/mra/article/view/6107>. Date accessed: 12 dec. 2024. doi: https://doi.org/10.18103/mra.v12i11.6107.
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Issue
Vol 12 No 11 (2024): November Issue, Issue 11, VOl.12
Section
Research Articles

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