We noticed you’re blocking ads

Thanks for visiting CRSTG | Europe Edition. Our advertisers are important supporters of this site, and content cannot be accessed if ad-blocking software is activated.

In order to avoid adverse performance issues with this site, please white list https://crstodayeurope.com in your ad blocker then refresh this page.

Need help? Click here for instructions.

Up Front | Sep 2008

Review of Two Courses: Correcting Regular and Irregular Astigmatism, Phakic IOLs

This is the fifth article in a series describing courses on cataract and refractive surgery at the University of Ulster.

This article describes courses five and six in the University of Ulster’s online program, the theoretical component for a 2-year Master of Science in cataract and refractive surgery. Course five reviews the correction of regular and irregular astigmatism, and course six reviews phakic IOLs.

Week 1. Following an introduction to the differences between corneal and total astigmatism, Johnny E. Moore, FRCOphth, PhD, provided an overview of techniques to treat astigmatism. Arcuate keratotomy, including the concept of coupling and its potential effects on spherical equivalent, was discussed. Additionally, methods to measure treatment efficacy and the effects of arcuate keratotomies on corneal shape were described.

Dimitri Azar, MD, delivered a lecture on the surgical options for treating astigmatism, consisting of photoastigmatic refractive keratectomy, LASIK, arcuate keratotomy, femtosecond arcuate keratotomy, limbal relaxing incisions, wedge resection, and laser arcuate resection.

Three case studies were presented. The first described a 33-year-old bank clerk who wanted refractive surgery. The clerk’s prescription was plano in her right eye (unaided 6/6) and 2.00 -6.00 X 25 in her left. Her topography revealed symmetrical, regular astigmatism, and her pachymetry was 520 µm in both eyes. Discussions involved the possibility of using two procedures in this case, such as arcuate keratotomy followed by excimer laser correction.

The second case was a 65-year-old retired man with bilateral cataracts and a bilateral prescription of -4.00 -3.50 X 90. His topography maps indicated 3.50 D of symmetrical, regular corneal astigmatism. His pachymetry readings were 500 µm. The patient always used rigid contact lenses for distance and reading glasses over his contact lenses for near work. Discussions included the operative plan and whether to address the astigmatism at the same time as or after cataract surgery.

The consensus was to treat the astigmatism at the time of cataract surgery with an incisional technique, later fine-tuning the refractive results with excimer laser treatment if residual astigmatism remained. The chance of overcorrecting the astigmatism was slight, considering it is more than 3.00 D. The group agreed that 3 months was a reasonable time between cataract surgery and laser enhancement.

The final case introduced a patient with postoperative astigmatism (6.00 D) following penetrating keratoplasty for keratoconus. The patient was contact lens intolerant. During the discussion, some students indicated that they would consider arcuate keratotomy with the option of laser fine-tuning if necessary. With a coupling ratio of 1:1, the final result following an arcuate keratotomy would be at best 3.00 diopters of sphere; however, surface laser treatment with mitomycin C would allow the surgeon to aim for emmetropia. It was argued that surgical intervention might initiate an episode of corneal graft rejection due to prolonged deepithelialization inducing inflammatory cytokines.

Week 2. Surgical and nonsurgical management of regular and irregular astigmatism were discussed. Jorge L. Alió, MD, PhD, presented a lecture on the treatment of irregular astigmatism following refractive surgery. This comprehensive lecture covered classification, topographic features, clinical studies, surgical interventions, wavefront-guided treatments, and case reports of irregular astigmatism.

Christine Astin, MPhil, BSc, FCOptom, shared her expertise in contact lens fitting after refractive surgery. The lecture considered indications, such as residual ametropia, anisometropia, astigmatism (including irregular astigmatism). Therapeutic indications were also discussed. She also presented the aims of fitting, with regard to the characteristics of a good fitting lens and important elements to consider when selecting the most appropriate lens, and she described the steps required for fitting both soft and rigid contact lenses. The problems with lens fitting and the resulting effects on the eye were also described.

Sunil Shah, FRCOphth, FRCS(Ed), FBCLA, presented the final lecture of the week on intrastromal corneal ring segments. Dr. Shah described the different types of intrastromal corneal rings and their indications, surgical techniques, and future trends.

Three case scenarios based on the lectures were discussed. The first described a patient who complained of night vision problems 1 year after PRK for bilateral -8.00 D prescriptions. The topography indicated a decentred ablation, and treatment options included topographic-linked ablations (Topolink software; Bausch & Lomb, Rochester, New York) and contact lenses.

The second case was a 45-year-old carpenter with a Y-shaped oblique thin scar reaching—but not penetrating—the deep stroma. The group discussed the appropriate and contraindicated uses of surface treatment with mitomycin C in scarred corneas. Alternatives such as phototherapeutic keratectomy and asymmetrical rotatory lamellar grafts were also mentioned.

The final case was a 26-year-old man who developed haze and irregular astigmatism in his right eye following PRK for -3.50 D. His prescription was -1.50 with 6/9 visual acuity. The reason for localized haze was previous ptosis surgery with resultant nocturnal inferior corneal exposure. The case was successfully managed with fluorometholone and artificial tears.1

Week 1. Jorge L. Alió, MD, PhD, reviewed the models of phakic IOLs and their particular complications. The discussion forum presented two clinical cases, a 42-year-old bilateral -18.00 D myope and a 35-year-old bilateral 7.00 D hyperope with a deep anterior chamber. The pros and cons of phakic IOLs versus refractive lens exchange were debated.

Students and tutors considered the advantages of phakic IOLs, including preservation of accommodation, improved refractive predictability over other modalities, and reduced vitreoretinal risks relative to lens exchange; the drawbacks, include the need for yearly endothelial follow-up for anterior chamber models, and the possibilities of iris and lens complications, iridocyclitis, and need for future surgery. Patients with phakic IOLs may require cataract surgery or treatment for physiologic age-induced reduction of the volume of the anterior chamber.

Students discussed the treatment of a patient 1 year after implantation of an angle-supported phakic IOL for bilateral 21.00 D. At the 28-year-old patient’s routine follow-up, he was happy with the results and described no difference between his two eyes; however a haptic entered the peripheral iridectomy in his right eye (Figure 1). Some students suggested close follow-up and no surgery, and others advised prompt IOL exchange, voicing concerns that movements of the lens will unavoidably lead to endothelial damage.

Week 2. Antonio Leccisotti, MD, PhD, addressed the concept of bioptics. The original meaning of bioptics (as described by Roberto Zaldivar, MD) is the combination of two refractive techniques, usually the first being intraocular and the second corneal. Bioptics can have two main purposes: fine-tuning a primary result or addressing large refractive errors. Reverse bioptics involves a secondary intraocular procedure (phakic IOL implantation or refractive lens exchange) to address a refractive error following a primary corneal procedure (eg, relevant regression after PRK).

Students and tutors discussed the following case: A 38-year-old teacher seeking refractive surgery had a refraction of -9.00 -5.00 X 10 in the right eye and -9.00 -2.00 X 170 in the left. Pachymetry showed 505 µm bilaterally. Students proposed surgical options including refractive lens exchange followed by excimer laser correction of residual astigmatism; phakic IOL followed by laser; and toric phakic IOL.

Another discussion surrounded the case of a macular hemorrhage without neovascular membrane that occurred 5 months after successful iris-fixated phakic IOL implantation for -15.00 D. The majority of students and tutors agreed that because of the long interval between surgery and the complication, the surgery was not responsible.

The last clinical case described a patient 1 week after implantation of an iris-fixated phakic IOL in the right eye for -16.00 D. The patient complained of severe halos during night driving (Figure 2). His refraction was 0.00 -1.25 X 160. All students agreed that recentering the IOL should solve or attenuate the inconvenience.

Students in this program have studied together online now for more than 5 months. At this point, there is an excellent tutor-to-student rapport; students are comfortable with voicing doubts, concerns, or opinions within discussion forums.

To recap thus far, the series of short courses has provided the following: introduction to refractive surgery, preoperative assessment in cataract and refractive surgery, excimer laser refractive surgery, complications of refractive surgery, and correction of regular and irregular astigmatism. The final four articles in this series will cover correction of presbyopia, cataract surgery, clinical governance, and medicolegal issues.

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, Générale-de-Santé Toscana, 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; e-mail: 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 states that he has no financial interest in the products or companies mentioned. He may be reached at e-mail: 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 tel: +44 0 2890368537l; e-mail: 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 tel: +353 0 16674778; e-mail: 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 tel: +44 0 7793226873; e-mail: t.moore@ulster.ac.uk.

Sunil Shah, FRCOphth, FRCS(Ed), 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; e-mail: sunilshah@doctors.net.uk.

Leccisotti A, Moore J. Haze after photorefractive keratectomy caused by iatrogenic lagophthalmos. J Cataract Refract Surg. 2006;32(8):1392-1394.