Original Research

Retinal nerve fibre layer and ganglion cell complex thickness in patients with keratoconus

Prianka Cuppusamy, Nokwanda Makhanya, Mbekezeli Methula, Kausar M. Essop, Duduzile Sibisi, Naseera Wohabally, Nonkululeko Gcabashe, Nishanee Rampersad
African Vision and Eye Health | Vol 77, No 1 | a417 | DOI: https://doi.org/10.4102/aveh.v77i1.417 | © 2018 Prianka Cuppusamy, Nokwanda Makhanya, Mbekezeli Methula, Kausar M. Essop, Duduzile Sibisi, Naseera Wohabally, Nonkululeko Gcabashe, Nishanee Rampersad | This work is licensed under CC Attribution 4.0
Submitted: 03 August 2017 | Published: 28 March 2018

About the author(s)

Prianka Cuppusamy, Discipline of Optometry, University of KwaZulu-Natal, South Africa
Nokwanda Makhanya, Discipline of Optometry, University of KwaZulu-Natal, South Africa
Mbekezeli Methula, Discipline of Optometry, University of KwaZulu-Natal, South Africa
Kausar M. Essop, Discipline of Optometry, University of KwaZulu-Natal, South Africa
Duduzile Sibisi, Discipline of Optometry, University of KwaZulu-Natal, South Africa
Naseera Wohabally, Discipline of Optometry, University of KwaZulu-Natal, South Africa
Nonkululeko Gcabashe, Discipline of Optometry, University of KwaZulu-Natal, South Africa
Nishanee Rampersad, Discipline of Optometry, University of KwaZulu-Natal, South Africa


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Abstract

Background: Keratoconus, a corneal ectasia, is associated with corneal thinning and altered optical media. Consequently, assessment of the visual field, optic nerve head and intraocular pressure measurements may be challenging in patients with keratoconus. Few studies have investigated posterior segment variables including the retinal nerve fibre layer (RNFL) and ganglion cell complex (GCC) thickness in patients with keratoconus.

Aim: To investigate RNFL and GCC thickness in patients with keratoconus.

Methods: A comparative quantitative research design was used. The sample consisted of 56 participants (28 with mild, moderate or severe keratoconus, and 28 controls) who accessed the optometry clinic at the University of KwaZulu-Natal. There was an equal distribution of male (n = 14) and female (n = 14) participants in the keratoconus and control groups. Most participants were black (n = 34) or Indian (n = 18). Corneal power and refractive error were assessed with the Oculus Keratograph and subjective refraction respectively. The iVue-100 optical coherence topography device was used to measure RNFL and GCC thickness. Data were analysed by descriptive and inferential statistics.

Results: The mean global RNFL thickness was slightly higher in the control group than the keratoconus group for the right (106 µm vs. 99 µm) and left (103 µm vs. 98 µm) eyes but these differences were not significant (p ≥ 0.057). For all RNFL quadrants, slightly lower mean RNFL measurements were found in the keratoconus group. The mean GCC thicknesses were marginally higher (3 µm – 6 µm) in the control group.

Conclusion: The RNFL and GCC thickness differences between patients with keratoconus and controls are not clinically significant. Therefore, abnormally reduced RNFL and GCC thickness measurements in patients with keratoconus warrant further investigation for other pathologies specifically glaucoma.

Keywords

retinal nerve fibre layer; ganglion cell complex; keratoconus; optical coherence tomography

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