Results of Collagen Crosslinking followed by posterior chamber toric implantable collamer lens implantation in patients with Keratoconus & High Myopia Dr Rajesh Fogla DNB, FRCS, MMed Senior Consultant, Corneal Surgeon Apollo Hospitals, Hyderabad Financial Disclosure – No Financial Interest

Collagen cross-linking Collagen cross-linking (CXL) using riboflavin phosphate- UVA (365nm) treatment leads to a significant increase in mechanical stiffness of the cornea. Increase in intra- and inter-fibrillar covalent bonds by photosensitized oxidation. Several studies have shown arrest of progression of keratoconus post CXL

Implantable Collamer Lens (ICL) Phakic IOL Approved for high myopia, thin corneas, suspicious corneal topography wherein LASIK is contraindicated Safe and predictable Reversible Visian Toric ICL * corrects astigmatism as well besides myopia *STAAR Surgical Company AG, Nidau, Switzerland

Keratoconus – Subset of patients have high myopia with astigmatism less than 6 diopters – Best spectacle corrected visual acuity is often > 20/40 in these patients – Patients desire better unaided vision Introduction In this study we evaluate visual outcome of collagen crosslinking followed by posterior chamber toric ICL implantation in patients with keratoconus & high myopia

Materials & Methods Prospective, non comparative, interventional case series of consecutive patients undergoing Collagen crosslinking followed by ICL implantation between March 2008 to September Keratoconus patients with astigmatism less than 6 diopters, minimal pachymetry of 400 microns, absence of corneal scarring and best spectacle corrected visual acuity (BSCVA) of 20/40 or better were included in study. (specular microscopy & anterior chamber depth as per requirements of ICL implantation were also assessed) Outcomes were measured in terms of uncorrected visual acuity (UCVA), BSCVA, refraction, topography and adverse events.

Surgical Technique Collagen Crosslinking Technique - Epithelial debridement followed by application of riboflavin phosphate 1% for 30mins and UVA (365nm) exposure for 30 mins. Eye patched with topical antibiotics till epithelial healing, followed by use of topical mild steroids, antibiotics and lubricants for one month Toric ICL implantation Technique – Surgery was performed under topical anesthesia in all cases. Axis of toric ICL was marked at the limbus. Standard technique of implantation recommended by the manufacturer was followed in all cases. Single surgical peripheral iridectomy (PI) was performed at 12 o clock position. Postoperatively patients received topical steroids, antibiotics, & lubricants for one month.

19 eyes of 15 patients (Male:Female = 11:4) All eyes underwent collagen crosslinking (CXL) followed by toric ICL implantation. Average duration between these two procedures 5.4 months (range 3-9 months) Pre CXL average keratometry values / 49.95, Post CXL / Pre toric ICL implantation data UCVA20/200 (0.1) BSCVA20/40 (0.5) Sphere (Refraction) Astigmatism (Refraction) Astigmatism (Corneal topography) Anterior Chamber Depth (mm) Specular Count (cells/mm2) Pachymetry (microns) Results

PrePost UCVA20/200 (0.1)20/40+ (0.62) BSCVA20/40(0.5)20/25+ (0.91) Astigmatism (Refraction) Astigmatism Corneal Topography Sphere (AutoRefractometer) Cylinder (AutoRefractometer) All patients had improvement in UCVA & BSCVA, Mean improvement of 5 lines of UCVA & 2 lines of BSCVA. None of the patients lost any line of BSCVA. No progression of keratoconus was noted at last follow up. (mean follow up 14 months) Results

Collagen Crosslinking – Trace corneal haze noted at 2-4 weeks post CXL which resolved by 8 weeks None of the patients lost BSCVA post CXL Toric ICL implantation Intraoperative - Nil Postoperative Pupillary block glaucoma 1 eye, due to blockage of tiny PI which resolved following Nd YAG laser enlargement Rotation of IOL requiring IOL repositioning 1 eye Excessive vaulting (1000 microns) 1 eye, resolved at one month postop possibly due to trapped viscoelastic behind IOL Complications

Discussion Keratoconus patients with astigmatism less than 6 diopters often have BSCVA of > 20/40. If associated with high myopia contact lens wear becomes necessary. Keratoconus is a progressive condition. CXL is effective in stabilizing progression of keratoconus In our study Toric ICL implantation provides fairly accurate correction of spherical power, & reduces astigmatism significantly to improve quality of unaided vision in keratoconic eyes with high myopia. Residual astigmatism of < 1 diopter may require spectacle correction

Conclusion Implantation of posterior chamber toric ICL to correct refractive error in patients with stable keratoconus appears to be a safe & effective procedure. Collagen crosslinking is essential to ensure stability of keratoconus prior to ICL implantation.

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