Normative profiles of neuroretinal rim area in a multiethnic Asian population: the Singapore Epidemiology of Eye Diseases study

AimsTo evaluate the normative profiles for neuroretinal rim area (RA) in a multiethnic Asian population.MethodsSubjects were recruited from the Singapore Epidemiology of Eye Diseases (2009–2015) study and underwent standardised examinations. RA measurements were performed using Cirrus high-definition optical coherence tomography (Carl Zeiss Meditec). Multivariable linear regression with generalised estimating equation model was used to evaluate the associations between demographic, systemic and ocular factors with RA.ResultsA total of 9394 eyes from 5116 subjects (1724 Chinese, 1463 Malay, 1929 Indian) were included in the final analysis. The mean (±SD) of RA was 1.28 (±0.23) mm2 for Chinese, 1.33 (±0.26) mm2 for Malays, and 1.23 (±0.23) mm2 for Indians. The 5th percentile value for RA was 0.94 mm2 for Chinese, 0.96 mm2 for Malay, and 0.89 mm2 for Indian. In multivariable analysis, following adjustment for age, gender, body mass index, diabetes mellitus, hyperlipidaemia, history of cataract surgery, axial length, intraocular pressure (IOP) and disc area, Indian eyes have smaller RA when compared with Malays (β=−0.074; 95% CI −0.090 to −0.058; p<0.001) and Chinese (β=−0.035; 95% CI −0.051 to −0.019; p<0.001), respectively. Additionally, older age (per decade, β=−0.022), male gender (β=−0.031), longer axial length (per mm, β=−0.025), spherical equivalent (per negative dioptre, β=−0.005), higher IOP (per mm Hg, β=−0.009) were associated with smaller RA (all p≤0.004).ConclusionIn this multiethnic population-based study, we observed significantly smaller RA in Indian eyes, compared with Chinese and Malays. This indicates the need of a more refined ethnic-specific RA normative databases among Asians.

Relationship between ocular risk factors for glaucoma and optic disc rim in normal eyes

AimTo study relationships between reported risk factors for glaucoma and neuroretinal rim area in normal eyes.MethodsThe Kumejima study participants, 3762 of the 4632 eligible Kumejima residents 40 years and older, underwent a detailed ocular examination including sequential disc stereo photography. In a randomly chosen eye of a subject whose both eyes met the inclusion criteria, fundus photographs of 2474 ophthalmologically normal eyes of the 2474 subjects were analysed by computer-assisted planimetry to measure the disc, rim and β-peripapillary atrophy (PPA) areas. The rim was divided into the superior and inferior halves by a line connecting the fovea and disc centre.ResultsThe disc, superior and inferior halves rim and β-PPA areas averaged 2.53±0.50 (SD), 0.82±0.15, 0.84±0.16 and 0.45±0.66 mm2. After adjustment for other systemic and ocular factors including age, disc and β-PPA areas, disc–fovea distance (p=0.013, 0.016) correlated positively and intraocular pressure (IOP) (p=0.004, 0.006) and axial length (AL) (p<0.000, 0.004) negatively with the superior and inferior halves rim area, respectively; central corneal thickness (CCT) (p=0.008) and mean blood pressure (mBP) (p=0.020) correlated positively and male gender (p=0.012) negatively only with the superior half rims.ConclusionsBesides previously reported risk factors for glaucoma such as age or IOP, thinner CCT, lower mBP and male gender were newly found to significantly correlate with smaller rim area only in the superior half disc, and a greater disc–fovea distance with greater superior and inferior half rim areas in normal adult eyes.

The Difference in Translaminar Pressure Gradient and Neuroretinal Rim Area in Glaucoma and Healthy Subjects

Purpose. To assess differences in translaminar pressure gradient (TPG) and neuroretinal rim area (NRA) in patients with normal tension glaucoma (NTG), high tension glaucoma (HTG), and healthy controls.Methods. 27 patients with NTG, HTG, and healthy controls were included in the prospective pilot study (each group consisted of 9 patients). Intraocular pressure (IOP), intracranial pressure (ICP), and confocal laser scanning tomography were assessed. TPG was calculated as the difference of IOP minus ICP. ICP was measured using noninvasive two-depth transcranial Doppler device. The level of significanceP< 0.05 was considered significant.Results. NTG patients had significantly lower IOP (13.7(1.6) mmHg), NRA (0.97(0.36) mm2), comparing with HTG and healthy subjects,P< 0.05. ICP was lower in NTG (7.4(2.7) mmHg), compared with HTG (8.9(1.9) mmHg) and healthy subjects (10.5(3.0) mmHg); however, the difference between groups was not statistically significant (P>0.05). The difference between TPG for healthy (5.4(7.7) mmHg) and glaucomatous eyes (NTG 6.3(3.1) mmHg, HTG 15.7(7.7) mmHg) was statistically significant (P< 0.001). Higher TPG was correlated with decreased NRA (r= −0.83;P= 0.01) in the NTG group.Conclusion. Translaminar pressure gradient was higher in glaucoma patients. Reduction of NRA was related to higher TPG in NTG patients. Further prospective studies are warranted to investigate the involvement of TPG in glaucoma management.