Posters

Ocular vs corneal wavefront-guided tissue-saving algorithms for irregular astigmatism in progressive keratoconus

Poster Details

First Author: D.Gore UK

Co Author(s):    B. Allan                    

Abstract Details

Purpose:

Simultaneous transepithelial photo-refractive keratectomy (TransPRK) and corneal collagen cross-linking (CXL) aims to reverse visual loss attributable to irregular astigmatism in early stage keratoconus without compromise to stabilization of disease progression. Here we compare ocular vs. corneal wavefront-guided tissue saving algorithms that exclusively treat irregular astigmatism in patients recruited to the TransPRK/CXL trial (NCT02208089).

Setting:

Refractive Surgery Service, Moorfields Eye Hospital, London

Methods:

Patients with progressive stage II-III keratoconus, LogMAR CDVA less than 0.00 and no ocular copathology were included. For purposes of comparison, tissue ablation treatments were programmed using both ocular and corneal aberrations (Ocular Wavefront Analyzer and Schwind Sirius, both Schwind Eye-tech Solutions, Kleinostheim, Germany). Optical zone diameters were matched for both programs. Ablation depth was minimised by exclusively treating dominant higher order aberrations only with no compensatory additional tissue removal to control for induced changes in sphere and cylinder. Ablation depths at the cornea center, cone apex and maximum depth were recorded.

Results:

Programmed treatments on 15 eyes of 12 patients are presented. Mean (SD) stromal ablation depths at the cornea center, cone apex and maximum ablation for ocular wavefront-guided treatments were 17 µm (± 7 µm), 29 µm (± 9 µm), 31 µm (± 11 µm) respectively. Mean (SD) stromal ablation depths at the cornea center, cone apex and maximum ablation for corneal wavefront-guided treatments were 33 µm (± 8 µm), 46 µm (± 12 µm), 50 µm (± 12 µm) respectively. At the thinnest part of the cornea (cone apex), the mean (SD) saving for ocular-wavefront guided treatments was 17 µm (± 10 µm) (p < 0.001)

Conclusions:

Ocular wavefront-guided treatments targeting irregular astigmatism ablate significantly less tissue compared with treatments based on anterior corneal surface aberrotmetry alone.

Financial Disclosure:

NONE