Following concepts discussed in the first course, the introduction to refractive surgery, the second course in the University of Ulster masters degree series on cataract and refractive surgery forms the basics of arguably one of the most important aspects of refractive surgery: preoperative assessment. (See description of the first course in the April 2008 issue of CRST Europe.)
WEEK 1
Steve Schallhorn, MD; Sunil Shah, FRCOphth, FRCS(Ed); and Antonio Leccisotti, MD, PhD, present a comprehensive five-part series on keratometry and corneal topography. This series explains the many changes in topography—from the theoretical and historical techniques used by Scheiner in 1619 to cutting-edge topographic techniques of today. Topography is necessary for preoperative planning, postoperative follow-up, and the detection of pathology. Currently, placido-disc and scanning-slit are the most common topography techniques. The concepts of elevation and curvature are introduced, along with their mathematical relationship and application across various commercially available topographers.
Dr. Leccisotti discussed the topography of corneal disease, focusing on keratoconus and practical advice on when to suspect keratoconus, such as the use of pattern recognition and quantitative descriptors. Topography maps with less obvious pathologies, including contact lens-induced corneal warpage, pellucid marginal degeneration, and corneal scarring were shared.
A keratoconus suspect case was presented, including the patient's corresponding axial and tangential maps. Participants analyzed the maps and discussed factors linked with keratoconus, such as patient age and refractive stability. Treatment options for suspect keratoconus were discussed, including surface treatment versus LASIK, corneal crosslinking with riboflavin, and intrastromal corneal ring segments.
A case of contact lens-induced corneal warpage was presented and compared with the appearance of early keratoconus. The warpage was due to long-term hypoxia; the cornea may appear keratoconic (eg, steepening, irregular astigmatism, reduced vision). Discontinuing contact lens use may help the warpage to subside; however, this can take months, and the reocurrence rate is high.
Map-dot fingerprint (ie, bilateral dystrophy of the epithelial basement membrane) was also discussed. In the case presented, the patient also suffered from epithelial erosions, and treatment options included artificial tears, contact lenses, oral tetracyclines, mechanical debridement, diamond burr polishing, anterior stromal puncture with needle or Nd:YAG, alcohol delamination, and phototherapeutic keratectomy (PTK).
WEEK 2
Dr. Leccisotti described the features of postsurgical corneal topography, particularly addressing the shapes of regular myopic and hyperopic ablation. He stressed the importance of tangential maps for the centration of the laser ablation and also described the principles and application of corneal endothelial evaluation by specular microscopy. The normal cell shape and density, as well as physiological cell loss in aging corneas, were discussed. The use of endothelial microscopy as a preoperative tool for phakic IOL and other lens-based surgery was also mentioned; endothelial microscopy is also important for follow-up after anterior-chamber phakic IOL implantation.
Several cases were discussed. In the first, a localized inferior steepening resembling keratoconus was evident on the tangential topography. Slit-lamp evaluation revealed a small stromal scar, inducing a focal curvature change (Figure 1).
The second case demonstrated a central flat area on tangential topography. The appearance of a hyperopic ablation was caused by another small stromal scar, in this case causing a depression in the corneal surface. In the third case, topographies of a keratoconic eye with superimposed rigid contact lens warpage changes were presented (Figure 2). Discussions helped participants to distinguish changes due to keratoconus (eg, high curvature, inferior steepening) and warpage (eg, small diffuse irregularities on Placido rings, print of the contact lens, increased or decreased curvature, and vertical or horizontal asymmetry).
Endothelial microscopy showed extensive cell loss due an unstable anterior chamber IOL after complicated cataract surgery. The features of the damaged endothelium and the various options to preserve corneal transparency (including IOL explantation) were discussed.
WEEK 3
The focus of lectures in week 3 was aspects of dry eye and binocular vision. Johnny Moore, FRCOphth, PhD, described the diagnosis of dry eye. Dry eye syndrome encompasses a group of disorders that affect the ocular surface and tear-film. The two main subclassifications of dry eye are aqueous deficiency and evaporative dry eye, both of which result in ocular surface signs and tear film instability. Dry eye can significantly impact visual function by increasing higher-order aberrations between blinks and inducing a fluctuation in vision. The value of questionnaires was stressed, along with the use of other tests to diagnose dry eye. The lecture also reviewed the literature on dry eye in relation to LASIK.
Counseling and managing patients requesting refractive surgery who have dry eye symptoms but good tear volume was discussed. Participants openly discussed commonly performed tests and how to appropriately advise patients. In one example, a patient who was considering refractive surgery had a positive family history of Sjˆgren syndrome. The literature was reviewed to determine the patient's risk for Sjˆgren syndrome and whether refractive surgery was advocated. The role of topical cyclosporine was deliberated.
An unusual post-LASIK dry eye case with punctate epithelial changes affecting only the inferior 2 mm of the flap edge was presented. The patient had reverse Bell phenomenon and nocturnal lagophthalmos. Treatment options included nocturnal taping and ointment.
Alison Finlay, BA, BPhil, DPhil, described various binocular vision situations that may arise during refractive surgery. The treatment of preexisting problems, such as accommodative strabismus and anisometropia, and the possibility of exacerbating a previously asymptomatic problem was described. Presentation of an anisometropic patient was presented; the group discussed the role of orthoptic tests and contact lens trials.
WEEK 4
This week was dedicated to biometry, with lectures from Drs. Shah and Leccisotti that discussed classic ultrasound biometry and its various formulas, including the Holladay 2 and Haigis formulas. The importance of different formulas depending on eye length was emphasized, as well as the difficulties arising from the different parameters required by each algorithm. Intraoperative autorefraction to calculate IOL power in special cases was also analyzed. The most appropriate applications are high myopia cataract surgery after corneal refractive surgery and intraoperative IOL verification when preoperative ultrasound biometry was deemed inaccurate. Additionally, autorefraction is appropriate when a previous ultrasound biometry is unavailable for IOL calculation for a phakic IOL.
The discussions addressed biometry formulas for short, average, and long eyes. All participants agreed on using SRK/T in long eyes and Hoffer Q in short eyes. In average eyes, most participants preferred SRK/T or Holladay 1.
SUMMARY
Corneal topography is mandatory, not only before corneal refractive surgery, but also when high-technology IOLs (eg, aspheric, multifocal) require a regular corneal shape. The diagnosis of corneal abnormalities requires adequate clinical data, especially slit-lamp evaluation, to rule out pseudokeratoconus and other confusing patterns. Assessment of tear film and endothelial microscopy complete the corneal evaluation. Bell phenomenom is an important test that is easily forgotten. A review of biometry techniques shows that an individually tailored approach is required for optimum IOL calculation.
Participants uniformly agreed that distance learning allowed them to balance studying with busy clinics and theater lists. Ophthalmologists were awarded 28 continuing professional development points as accredited by the Royal College of Ophthalmologists; optometrists were awarded eight points as accredited by Vantage Technologies General Optical Council continuing education and training scheme.
Antonio Leccisotti, MD, PhD, is a Visiting Professor at the School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, and Director of the Ophthalmic Department, Casa di Cura Rugani, Siena, Italy. Dr. Leccisotti states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +39 335 8118324; fax: +39 0577 578600; leccisotti@libero.it.
Colm McAlinden, BSc(Hons), MCOptom, is an optometrist and refractive surgery PhD Student, School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland. Mr. McAlinden may be reached at colm.mcalinden@gmail.com.
Damien McConville, MSc, MBCS, FHEA, is a Learning Technologist at the Institute of Lifelong Learning, University of Ulster. Dr. McConville states that he has no financial interest in the products or companies mentioned. He may be reached at +44 0 2890368537; d.mcconville@ulster.ac.uk.
Johnny E. Moore, FRCOphth, PhD, is a Visiting Professor at the School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland, and Department of Ophthalmology, Mater Hospital, Belfast Hospital Trust Northern Ireland, and Director of Leeson Eye Institute, Dublin, Ireland. Dr. Moore states that he has no financial interest in the products or companies mentioned. He may be reached at +353 0 16674778; johnnymoorebal@gmail.com.
Tara Moore, PhD, NTF, is a Course Director and Senior Lecturer at the School of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland. Dr. Moore states that she has no financial interest in the products or companies mentioned. She may be contacted at +44 0 7793226873; t.moore@ulster.ac.uk.
Sunil Shah, FRCOphth, FRCSEd, FBCLA, is a Visiting Professor at the School of Biomedical Sciences, University of Ulster, Coleraine, UK, Visiting Professor at the School of Life & Health Sciences, Aston University, Birmingham, UK, Medical Director, Midland Eye Institute, Solihull, UK, Consultant Ophthalmic Surgeon, Heart of England Foundation Trust, Birmingham, UK, and Consultant Ophthalmic Surgeon, Birmingham & Midland Eye Centre, Birmingham, UK. Dr. Shah states that he has no financial interest in the products or companies mentioned. He may be reached at tel: +441217112020; fax: +441217114040; sunilshah@doctors.net.uk.
