Preop evaluation before refractive IOL implantation

Miami-Preoperative evaluation of patients scheduled to undergo implantation of a refractive IOL is mandatory for obtaining the best postoperative results. Topography, optical coherence tomography of the macula, and fluorescein staining of the cornea are critical when evaluating patients before cataract surgery. William Trattler, MD, in private practice in Miami, described how he manages these patients.

Blepharitis is a common ocular disorder, and to determine just how common it is, Dr. Trattler participated in a study run by Jodi Luchs, MD, that evaluated 200 eyes of 100 patients at two centers who were scheduled to undergo cataract surgery. The study found that 59% of patients about to undergo cataract surgery had blepharitis. A key finding in the study was that the tear film break-up time was less than 7 seconds in 61% of patients.

“Almost two-thirds of patients in the study had an abnormal tear film break-up time,” Dr. Trattler said.

Dr. Trattler also conducted a second nine-site study to determine the prevalence of dry eye in patients aged 55 and older who were scheduled to undergo cataract surgery. In a questionnaire, patients were asked about the presence of dry eye symptoms; 59% of patients denied experiencing a foreign body sensation, and 28% reported a foreign body sensation just some of the time. The study found that although most patients scheduled for cataract surgery were asymptomatic or minimally symptomatic for dry eye, the vast majority of patients scheduled for cataract surgery had dry eye. The average tear break up time of the more than 200 eyes evaluated was 4.93 seconds; with 61% having a tear film break-up time of 5 seconds or less, and 81% scoring 7 seconds or less. Central corneal staining was present in 45.1% of eyes, and 46% of patients had abnormal Schirmer’s test scores.

“Do not expect patients with cataracts to complain of dry eye as we typically see with our younger patients,” Dr. Trattler said. “Since moderate dry eye affects the quality of vision, it is important to determine whether dry eye is part of the reason that patients with cataracts are reporting significant visual complaints.”

An abnormal tear film break-up time can affect the preoperative keratometry and topography assessments. Optical biometer (IOL Master, Carl Zeiss Meditec) measurements, which are routinely used in many clinical practices, were affected and patients with dry eye had very inconsistent keratometry measurements. Dr. Trattler noted a case example of one representative patient with dry eye in which the magnitude of the astigmatism differed among the three measurements made by the optical biometer (i.e., 1.79, 1.46, and 1.15 D). The topography measurements also were abnormal in this patient.

“This patient had dry eye, which explains the erratic values,” he said.

This patient was treated preoperatively with a topical prednisolone acetate 1% and cyclosporine (Restasis, Allergan), which, 1 week later, resulted in more consistent astigmatism measurements and improved topography.

In another patient with dry eye and meibomian gland dysfunction, the astigmatism powers measured with the optical biometer were 0.81, 1.15, and 0.34 D, also very erratic; the topographic measurement indicted keratoconus. The patient had a rapid tear film break-up time with a great deal of corneal staining. Treatment with topical prednisolone acetate 1% and azithromycin (AzaSite, Merck) resulted in improved keratometry values and less asymmetry of the ocular surface.

The impact on IOL selection could also be seen in the case of a patient who had central corneal staining. The patient was evaluated using the optical biometer, and the appropriate lens power was determined to be a 20-D multifocal IOL (Tecnis, Abbott Medical Optics). The patient was treated with cyclosporine 0.1% twice daily and prednisolone acetate 1% four times daily for 1 week, and the repeat optical biometer measurements resulted in a change in the optimal IOL power to a 21-D lens.

“The preoperative measurements obtained before the ocular surface is treated indicate the importance of identifying and treating these patients before surgery,” Dr. Trattler concluded. “Careful evaluation of patients scheduled for cataract surgery with fluorescein staining of the cornea to evaluate tear break-up time and corneal staining, as well as to help pick up subtle cases of epithelial basement membrane dystrophy, can be helpful in improving outcomes with refractive IOLs.”

Dr. Trattler is a consultant for Abbott Medical Optics, Allergan, and Inspire Pharmaceuticals.

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