Purpose: This study was conducted to evaluate the effect of pupillary dilation on retinal nerve fiber layer (RNFL) thickness as measured by scanning laser polarimetry (SLP) in cataractous and noncataractous eyes. Methods: The study included 31 eyes of 31 consecutive patients (mean age, 62.5 ±14.0 years; range, 30-76 years). Eyes with refractive error exceeding 5.0 D sphere or 2.0 D cylinder, nonlenticular media opacity, cup-to-disc ratio >0.9, corneal disease, ocular inflammation, or previous intraocular surgery were excluded. A standard reticule was used to measure pupillary diameter. Cataract grade was evaluated by a single observer using the Lens Opacities Classification System (LOCS III). RNFL thickness measurements were obtained by means of SLP before and after pupillary dilation. Results: Of the patients, 10 had clear lenses and 21 had variable degrees of lenticular opacification. In four eyes, imaging could not be performed because of dense cataracts. Mean pupillary diameters before and after dilation were 2.5 ± 0.7 mm and 7.3 ± 1.1 mm, respectively. There were no significant differences in global RNFL thickness before and after dilation in noncataractous and cataractous eyes. Among cataractous eyes in which imaging was possible, there was no correlation between difference in RNFL thickness before and after dilation and nuclear opalescence, nuclear color, and cortical and posterior subcapsular grading of the LOCS III score. Six of 27 eyes (22.2%) had a change of more than 10% in RNFL thickness after pupillary dilation. Conclusion: Although pharmacologic mydriasis does not statistically alter RNFL thickness as measured by SLP, approximately one fifth of such eyes will have a change of more than 10% in retardation. Uniformity in pupil size is recommended when longitudinally evaluating RNFL measurements.
- Retinal nerve fiber layer, thickness
- Scanning laser polarimetry
ASJC Scopus subject areas