Elsevier

Ophthalmology

Volume 114, Issue 5, May 2007, Pages 921-926
Ophthalmology

Original Article
Normal Age-Related Decay of Retinal Nerve Fiber Layer Thickness

Presented as a poster at: American Academy of Ophthalmology Annual Meeting, November 2006, Las Vegas, Nevada.
https://doi.org/10.1016/j.ophtha.2007.01.023Get rights and content

Purpose

To determine the normal age-related loss of retinal nerve fiber layer thickness (RNFLT) as measured on Stratus optical coherence tomography (OCT 3; Carl Zeiss Meditec, Dublin, CA) in an Asian Indian population.

Design

Prospective, cross-sectional, observational study.

Participants

One hundred eighty-seven eyes of 187 normal subjects (age range, 5–75 years) who satisfied the inclusion and exclusion criteria were included. The subjects were defined as normal if they had visual acuity of 20/30 or better, intraocular pressure less than 22 mmHg with normal optic disc, and no ocular abnormality.

Methods

All patients underwent complete ophthalmic evaluation including imaging with Stratus OCT 3. Simple linear regression was performed to study the effect of age on RNFLT, with age as the independent variable and RNFLT as the dependent variable. Spearman’s correlation was studied between the age and RNFLT. An analysis of variance was applied to compare RNFLT between the different age groups. The chi-square test also was used to evaluate the relationship between age and RNFLT.

Main Outcome Measure

Effect of age on RNFLT.

Results

One hundred eighty-seven eyes of 187 normal subjects were analyzed. Mean age±standard deviation was 33.0±19.7 years (range, 5–75). Average RNFLT and RNFLT by quadrant demonstrated the tendency of RNFLT to decrease with increasing age, especially after age 50 years. Average RNFLT demonstrated a negative slope of 0.16 μm/year (95% confidence interval [CI], −0.1 to −0.24). By quadrant, the superior average (negative slope, –0.23 μm/year; 95% CI, −0.1 to −0.34) showed a maximum tendency to decline with age, whereas in the inferior quadrant (negative slope, −0.08 μm/year; 95% CI, 0.05 to −0.24), the age-related decay was minimal. Six clock-hour RNFLT had a least negative slope of −0.022 μm/year (95% CI, −0.08 to −0.1). Chi-square test results showed a significant inverse relationship between age and average RNFLT (P = 0.01).

Conclusions

Age-related retinal nerve fiber layer (RNFL) loss is not uniform in all the quadrants, with maximum loss in the superior quadrant, and seems to reach a maximum after the age of 50 years. Furthermore, it seems that inferior quadrant RNFL is more resistant to loss.

Section snippets

Patients and Methods

The study was conducted on consecutive patients attending the outpatient services of the L. V. Prasad Eye Institute from July 2004 to February 2006 who satisfied the inclusion and exclusion criteria. The study protocol was approved by the ethics committee of the L. V. Prasad Eye Institute, Hyderabad. The methods applied in the study adhered to the tenets of the Declaration of Helsinki for the use of human subjects in biomedical research.

All the subjects underwent complete ophthalmic

Results

A total of 201 eyes (201 subjects) were evaluated; 14 eyes were excluded because of poor image quality on OCT. One hundred eighty-seven eyes of 187 normal subjects were analyzed. Mean age±SD was 33.0±19.7 years (range, 5–75), the male-to-female ratio was 114:73, and right-to-left eye ratio was 101:86. No significant difference was found in RNFLT between males and females (P = 0.6). Table 1 shows the average RNFLT by quadrant and clock hour in all the eyes. The RNFLT was at a maximum in the

Discussion

Retinal nerve fiber layer loss over and above age-related loss is what is important in making a diagnosis of glaucoma. With the GDx VCC and OCT, if it becomes possible to quantify normal age-related RNFL loss, then it may become possible to attribute the RNFL loss that may be the result of glaucoma only. Reproducibility and validity of OCT already has been demonstrated.16, 17, 18 Although our article does not report diagnostic accuracy of a machine, we followed the Standards for Reporting of

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    Manuscript no. 2006-1005.

    Supported in part by Hyderabad Eye Research Foundation, Hyderabad, India.

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