The effectiveness of three-step treatment for keratoconus with correction of associated ametropia

Abstract

Background. Keratoconus is a progressive ectatic disease with thinning and bulging of the cornea structure. It is characterized by a bilateral and usually asymmetric course, which is manifested by the formation of irregular astigmatism. Several different combinations of treatments are currently being used to stop the progression of keratoconus and increase visual acuity.

Aim. To assess the effectiveness of three-step treatment for progressive keratoconus to stabilize the cornea, eliminate its irregularity and achieve maximum visual acuity.

Material and methods. A triple combined treatment was applied to 48 patients (24 women and 24 men) with stage 2–3 keratoconus (67 eyes) aged 16–31 years (mean age 24.4±0.21 years) at the National Center of Ophthalmology named after Academician Zarifa Aliyeva between 2017 and 2019. It consisted of intrastromal corneal ring implantation, corneal crosslinking after 24 hours, and topography-guided transepithelial photorefractive keratectomy (PRK) after 8 months. All patients underwent complex examinations: uncorrected visual acuity and best spectacle-corrected visual acuity, autorefractometry, non-contact tonometry, corneal topography, tomography, optical coherence tomography of the anterior segment, ultrasound pachymetry. The statistical significance of the difference between the data before and after treatment was assessed by using analysis of variance in the “data analysis” package of the Microsoft Excel software.

Results. Uncorrected visual acuity before surgery was 0.2±0.041 and ranged between 0.04 and 0.3. Twelve months after surgery, uncorrected visual acuity significantly improved in all patients; its average value was 0.5±0.048 and ranged between 0.2 and 0.7. An improvement was observed in best spectacle-corrected visual acuity, which ranged between 0.2–0.5 before surgery and 0.4–0.8 after surgery. After intrastromal corneal ring implantation + corneal crosslinking + topography-guided transepithelial-PRK, residual refractive errors of the cornea were eliminated. The maximum keratometry (Kmax) decreased from 46.1–57.3 D to 42.1–49.9 D (M and SD before surgery 50.0±1.5 and after surgery 45.2±1.4, p=0.009), astigmatism also decreased from 5.25–9.25 to 0.5–3.25 cyl (M and SD before surgery 4.61±0.50 and after surgery 4.18±0.48, p=0.025). No complications were observed during and in the postoperative period.

Conclusion. The three-step treatment of progressive keratoconus will avoid the need for keratoplasty and achieve maximum visual acuity, minimize the number of aberrations and halts the progression of keratoconus.

Keywords

keratoconus / intrastromal rings / transepithelial topographic photorefractive keratectomy / collagen crosslinking

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