Eyeworld

Cynthia Matossian, MD, FACS by Cynthia Matossian, MD, FACS Preop planning and postop outcomes in patients with dry eye The neglected refractive interface: Impact of the tear film on refractive cataract surgery outcomes refractive cataract surgery and delay measurements until after treatment for dry eye, patients may be dissatis- fied with their outcomes. A recent patient was treated with preservative-free artificial tears for 2 weeks. When she returned for her preoperative cataract mea- surements, however, she had 1.5 D cylinder and her ocular surface remained irregular. I further delayed her preoperative calculations and intensified her treatment, prescrib- ing loteprednol gel and cyclosporine ophthalmic emulsion 0.05%, and oral omega-3s in addition to her preservative-free tears. Approximate- ly 2 weeks later, her ocular surface had improved significantly and her cylinder had decreased to 0.7 D. If I had not delayed the patient's measurements, her IOL power calculations would have been incorrect and she would have been unhappy with her visual outcome. In a case managed by William Trattler, MD, based on the patient's keratometry measurements, lens power calculations suggested a 20 D Tecnis multifocal IOL was required; however, Dr. Trattler opted to treat the patient's ocular surface before repeating the biometry. After ocular surface treatment, the optimal IOL power changed to 21 D. If the initial 20 D IOL had been implanted, the patient would have had a 1 D refractive surprise with a multifocal IOL and would not have been satisfied with the surgical outcome. Impact of dry eye on surgical planning Dry eye also affects surgical deci- sions when correcting astigmatism. A gas permeable contact lens wearer with –11 D myopia had a very ectatic cornea, with pellucid marginal degeneration. The patient was displeased when asked to stop wearing his contact lenses until his K readings stabilized. After the K readings sta- bilized, the patient had more than 4.5 D astigmatism, but had surgery not been delayed until the K read- ings and ocular surface stabilized, calculations would have indicated an SN6AT8 with minimal residual astigmatism (0.1 D). After the tear film and cornea stabilized, he needed an SN6AT9 with a residual corneal astigmatism of 1.5 D, which had to be factored into his implant calculation. I Preoperative calculations may be misleading if performed before dry eye is treated O cular surface disease can have a cascading effect on refractive cataract sur- gery. If surgeons neglect the tear film, significant consequences may result, affecting surgical data and planning and the patient's visual outcome. Therefore, it's important that we understand the impact of dry eye and treat it before beginning preoperative calculations. Effects on preoperative measurements Dry eye may affect keratometry, topography, wavefront imaging, and intraocular lens (IOL) power calculation. Therefore, I aggressively treat ocular surface disease before performing preoperative calculations (see sidebar). Occasionally this may cause a significant delay, but in most cases I am able to schedule biometry within a few weeks. If surgeons do not identify ocular surface disease before A patient with –11 D myopia had a very ectatic cornea. The initial calculations showed an SN6AT8 to be ideal with minimal residual astigmatism (0.1 D); after tear film and cornea stabilization 2 months later, his calculations indicated the need for an SN6AT9 with a residual corneal astigmatism of 1.5 D.

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