Multifocal Electroretinogram in Keratoconus Patients without and with Scleral Lenses

ABSTRACT

Purpose: To investigate changes in the multifocal electroretinogram (mfERG) response in eyes with keratoconus when corrected with scleral lenses (SL) compared with the best correction in glasses.

Methods: The mfERG responses in 10 eyes with keratoconus were recorded with the best correction using both a trial frame (baseline) and a hexafocon A SL using an electrophysiological diagnostic system. Electrophysiologic measurements were performed with the pupils fully dilated with instillation of 1% phenylephrine. The implicit time (milliseconds), amplitude (nV), and response density (nV/deg²) of the peaks (N1, P1, and N2) were analyzed for the total mfERG response, six rings and four quadrants of the retina, and compared between the two conditions.

Results: All eyes had a significant improvement in visual quality with the SL compared with baseline (mean differences, 0.26 ± 0.17 and 0.22 ± 0.13 logarithm of the minimum angle of resolution for high- and low-contrast visual acuity, respectively). The peaks implicit times of the mfERG responses did not show significant differences (p > .05). The P1 amplitude decreased in all the retinal areas with the SL. Only the total retinal response and the nasal quadrants reached significance (p ≤ 0.044). The P1 response density in ring 1 was on average higher with the SL, but not significantly so. The decline in P1 response density from the center to the periphery was more abrupt with the SL, and was more similar to the response density distribution of a typical subject, without a corneal pathology.

Conclusions: mfERG did not show any change associated with retinal disease in young patients with keratoconus. Although the improved visual performance was not associated with changes in the mfERG response, the correction of irregular astigmatism with the SL helps exclude the optical effect induced by keratoconus.

KEYWORDS:

• Multifocal electroretinography
• keratoconus
• scleral lens
• retinal response

Disclosure statement

The authors declare that they do not have any proprietary or financial interest in any of the materials mentioned in this article.

Ethics approval

All procedures performed in studies involving human participants were under the ethical standards of the Ethics Subcommittee for Health and Life Sciences of the University of Minho and followed the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Availability of data and material

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

Additional information

Funding

This project was supported by Fundação para a Ciência e a Tecnologia (FCT) in the framework of projects PTDC/FIS-OPT/0677/2014, the FCT Strategic Funding UID/FIS/04650/2013, FCT-SFRH/BPD/92365/2013 and SFRH/BD/136684/2018, through MCTES, ESF and EU funds.