Elsevier

Ophthalmology

Volume 113, Issue 6, June 2006, Pages 985-991
Ophthalmology

Original Article
Effect of Corneal Drying on Optical Coherence Tomography

https://doi.org/10.1016/j.ophtha.2006.02.018Get rights and content

Purpose

To determine the effect of corneal drying on the outcome of optical coherence tomography (OCT).

Participants

Seventeen normal participants (mean age, 39±12 years).

Methods

Subjects underwent a series of peripapillary circular StratusOCT scans (version 3.0; Carl Zeiss Meditec, Inc., Dublin, CA) in a randomly selected eye. Baseline scan sets were acquired, and thereafter, blinking was prevented by taping the eyelid. Eyelid taping was immediately followed by 6 to 8 serial scan sets, each separated by 20 seconds. After removing the eyelid tape, 3 additional scans were acquired at 1, 2, and 4 minutes of blinking freely.

Main Outcome Measures

The analyzed outcome measures were scan quality as defined by signal-to-noise ratio (SNR) and signal strength (SS) provided by the built-in OCT software and mean nerve fiber layer (NFL) thickness.

Results

Significant reductions in SNR, SS, and NFL were noted at each scanning point in the drying phase (for each, P<0.015, paired t test) except for NFL thickness measurements acquired at 140 and 160 seconds. The reduction in NFL thickness exceeded the 95% confidence limit of the reported reproducibility error of StratusOCT after 15 seconds of corneal drying. After 1 and 2 minutes of blinking freely, there was still a significant reduction in NFL thickness compared with the baseline value, which was no longer evident at the 4-minute scan.

Conclusions

Corneal dryness affects OCT scan quality and measured NFL thickness after a short exposure time. It is recommended to instruct those who are scanned to blink frequently or to instill artificial tears.

Section snippets

Patients and Methods

Healthy volunteers were enrolled in this prospective study. Institutional review board and ethics committee approval was obtained for the study, and all participants gave their informed consent to participate in the study. The study followed the principles of the Declaration of Helsinki.

Each participant underwent a full medical and ocular history, and a detailed ocular examination was performed, including visual acuity and slit-lamp and fundus examinations.

The healthy volunteers were recruited

Results

Seventeen healthy participants were enrolled in the study. The mean age of the group was 39±12 years. Six of the participants were male, and 6 of the 17 eyes (35%) were right eyes. All participants underwent a fluorescein staining examination, with no surface abnormalities or staining irregularities. Mean BUTs for all participants was 13.9±5.5 seconds. All participants were scanned to at least 80 seconds of drying time. The number of scans of sufficient quality to calculate NFL thickness

Discussion

The study evaluated the effect of extended corneal exposure, with resulting corneal drying, on the quality of OCT scans and the quantitative measurements obtained by those scans. Prolonged corneal exposure led to significant reduction both in scan quality and NFL thickness measurements (Table 1; Figure 4, Figure 5). The reduction in scan quality led to a substantial decrease in the percentage of scans that qualified for analysis (Fig 3).

The SNR sharply declined at the early stages of the drying

References (14)

There are more references available in the full text version of this article.

Cited by (60)

  • Optical coherence tomography-signal strength index following trifocal and monofocal intraocular lens implantation

    2021, Photodiagnosis and Photodynamic Therapy
    Citation Excerpt :

    Improvement of the optical coherence tomographic image quality has been reported in several studies following cataract extraction and intraocular lens implantation [4–7]. The majority of them evaluated those eyes implanted with monofocal intraocular lens’ while the influence of bifocal/trifocal intraocular lens implantation on the optical coherence tomography quality has been controversial [8,9]. In a comparative study, retinal nerve fiber layer thickness measurements of the patients implanted with a trifocal intraocular lens were reported to be higher than those implanted with a monofocal intraocular lens [9].

  • Reply

    2021, Ophthalmology
View all citing articles on Scopus

Manuscript no. 2005-667.

Drs Stein and Wollstein shared equally in preparation of the manuscript.

Supported in part by the National Institutes of Health, Bethesda, Maryland (grant nos.: R01-EY013178-6, P30-EY008098); The Eye and Ear Foundation, Pittsburgh, Pennsylvania; and an unrestricted grant from Research to Prevent Blindness, Inc., New York, New York.

Dr Schuman receives royalties for intellectual property licensed by the Massachusetts Institute of Technology to Carl Zeiss Meditec, Inc.

View full text