Abstract
Purpose:
The current trend in early glaucoma diagnosis is based on the detection of structural damage, including the ganglion cell complex (GCC), as it is known that there must be lost about 30% of these cells to detect changes in the visual field. We performed a prospective, cross-sectional, observational and analytic study to determine the thickness of ganglion cell layer in our population measured by optical coherence tomography (OCT). We hypothesized that thickness of GCC in Mexican mestizo patients is similar to that reported in the literature and there is no relationship with sex, dominant eye, and refraction.
Methods:
Patients were recruited consecutively and voluntary (N=79); Mexican mestizo patients, older than 18 years, indistinct sex, sphere -4.00 to +4.00 diopters (D), cylinder ≤ 2.00 D, intraocular pressure between 8 and 21 mmHg: patients with media opacity, macular disease, glaucoma/ glaucoma suspects, ocular trauma or surgery, and diabetes mellitus were excluded. All patients underwent a medical history and ophthalmological examination, refraction; a tomography of the ganglion cell layer was performed to all selected patients. We conducted an analysis of intraobserver agreement of the OCT images (20 patients, 2 OCT images per patient). Differences according to sex and dominant eye were evaluated with Student’s t test. We performed a ANOVA for refraction and thickness in the different macular sectors. A Pearson correlation was performed for age and thickness.
Results:
The average age was 41.37 ± 16.2 years (60.75% female). We obtained correlation coefficient (intraobserver agreement) of 0.98 (95% CI 0.94-0.99); we also performed a Bland-Altman plot. The average thickness was 84.04 ± 5.40 μm. The thicker sector was the superior nasal. We observed no differences in thickness according to sex (female 84.29 ± 5.39 μm vs male 83.65 ± 5.48 μm, p=0.60), age (p=0.09, r=-0.19, r2=0.039), refraction (p=0.41) and ocular dominance (84.04 ± 5.40 μm vs 84.14 ± 5.28 μm, p=0.90).
Conclusions:
The analysis of GCC using OCT is a reproducible and non-contact study. Our results were consistent with our hypothesis. The possibility to determine the normal average thickness of the complex of ganglion cells in our population represents a reference point from which we can consider a thinning of this layer helping us to make earlier diagnosis of glaucoma.