Journal of Refractive Surgery

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Intraoperative Autorefraction for Combined Phakic Intraocular Lens Explantation and Cataract Surgery

Antonio Leccisotti, MD, PhD

Abstract

ABSTRACT

PURPOSE: To evaluate intraoperative auto refraction during combined phakic intraocular lens (PIOL) explantation and cataract surgery.

METHODS: Phakic intraocular lens explantation was followed by crystalline lens emulsification and reformation of the anterior chamber with balanced salt solution. Autoref raction was performed intraoperatively with the Nikon Retinomax 2, and the IOL power was calculated using a formula for myopic eyes: IOL for emmetropia = 1.3 x aphakic spherical equivalent refraction + 1.45.

RESULTS: Nineteen myopic eyes of 15 patients with anterior or posterior chamber PIOL (including 6 eyes that had undergone photorefractive keratectomy) were treated. Two months postoperatively, mean spherical equivalent refraction was -0.56 ?0.40 diopters (D) (range: Oto -1.50 D).

CONCLUSIONS: In myopic eyes, intraoperative a uto- refraction provided a simple and reliable method to calculate IOL power in combined PIOL explantation and cataract surgery. [J Refract Surg. 2007;23:931-934.]

Abstract

ABSTRACT

PURPOSE: To evaluate intraoperative auto refraction during combined phakic intraocular lens (PIOL) explantation and cataract surgery.

METHODS: Phakic intraocular lens explantation was followed by crystalline lens emulsification and reformation of the anterior chamber with balanced salt solution. Autoref raction was performed intraoperatively with the Nikon Retinomax 2, and the IOL power was calculated using a formula for myopic eyes: IOL for emmetropia = 1.3 x aphakic spherical equivalent refraction + 1.45.

RESULTS: Nineteen myopic eyes of 15 patients with anterior or posterior chamber PIOL (including 6 eyes that had undergone photorefractive keratectomy) were treated. Two months postoperatively, mean spherical equivalent refraction was -0.56 ?0.40 diopters (D) (range: Oto -1.50 D).

CONCLUSIONS: In myopic eyes, intraoperative a uto- refraction provided a simple and reliable method to calculate IOL power in combined PIOL explantation and cataract surgery. [J Refract Surg. 2007;23:931-934.]

Cataract formation is not uncommon in myopic eyes implanted with a phakic intraocular lens (PIOL),1 resulting from iridocyclitis, IOL contact,23 aging, or simply because high myopia is a risk factor.4 When simultaneous PIOL removal and phacoemulsification are performed, calculation of Pseudophakie IOL power by ultrasound biometry can be laborious and inaccurate.5 Moreover, in cases in which PIOL implantation was followed by excimer laser enhancement (bioptics), the sources of error become numerous.

Intraoperative autorefraction does not require axial length or keratometry, and thus has been proposed for IOL calculation after corneal refractive surgery6 and in highly myopic eyes.7 This study assessed intraoperative autorefraction in combined PIOL explantation and cataract surgery in a myopic series, including eyes that underwent photorefractive keratectomy (PRK).

PATIENTS AND METHODS

From 2002 to 2006, combined PIOL explantation, phacoemulsification, and in-the-bag IOL implantation was performed on 19 myopic eyes of 15 patients. Surgery was performed under topical or peribulbar anesthesia. Sixty minutes and 30 minutes prior to surgery, levofloxacin 0.3% and tropicamide 1% eye drops were instilled. The microscope light was kept at the minimum possible intensity. A sclerocorneal tunnel was made on the steepest meridian, and the anterior chamber was filled with an ophthalmic viscosurgical material (Pro vise; Alcon Laboratories Ine, Ft Worth, Tex). The tunnel width depended on the size of the PIOL (3.2 mm for foldable IOLs and 5.5 mm for rigid IOLs). The PIOL was removed, and in cases that required a large tunnel, two single radial 10-0 nylon sutures were temporarily placed to reduce the tunnel width to 3.2 mm. In cases with previous iridocyclitis, posterior synechiae were freed by a blunt spatula, and the pupil was enlarged using four disposable iris retractors.

The formula was obtained by linear regression analysis of myopic eyes that had undergone refractive lens exchange, studying the relation between the aphakic autorefraction and the IOL power for emmetropia.7 The effect of epithelial drying or of excess BSS on the cornea was controlled by frequent irrigation during the entire surgical procedure. After the final corneal irrigation, the surgeon waited 5 seconds before performing autorefraction to allow any excess BSS to drain.

Finally, the anterior chamber was filled with Provise, a foldable acrylic IOL with a 118.2 A-constant was implanted in the capsular bag, and iris retractors (if used) were removed. Next, the ophthalmic viscosurgical material was aspirated out, and the wound was closed using one or more 10-0 Vicryl (Ethicon Ine, Somerville, NJ) radial sutures. Levofloxacin 0.3% and dexamethasone 0.1% eye drops were administered four times daily for 15 days.

RESULTS

Mean patient age was 47.3 ?5 years (range: 38 to 55 years). Mean preoperative spherical equivalent refraction was -16.27?3.56 D (range: -9.00 to -23.00 D). Preoperatively, an angle-supported PIOL was present in 13 eyes, an iris-fixated PIOL was present in 2 eyes, and a posterior chamber PIOL was present in 4 eyes. Excimer laser enhancement (bioptics) had been performed in 6 eyes by PRK. The features of cataracts and the length of time between PIOL implantation and cataract surgery are shown in the Table.

In all cases, surgery was uneventful and autorefraction was completed; in no case did the presence of iris retractors hamper autorefraction. The IOL power chosen aimed for emmetropia, but when the exact power was unavailable (eg, 0.25-D increments), a myopic error was always preferred. The main outcome measure was subjective spherical equivalent refraction at 5 m 2 months postoperatively. Mean spherical equivalent refraction was -0.56?0.40 D (range: 0 to -1.50 D). Mean prediction error was ? 0.18?0.35 D (range: +0.25 to ? 1.25 D), and mean absolute prediction error was 0.23?0.31 D (range: 0 to 1.25 D). Spherical equivalent refraction was within ?0.50 D of the attempted correction in 11 (58%) eyes and within ?1.00 D in 17 (89%) eyes; spherical equivalent refraction was not greater than 2.00 D of attempted correction in any eye. Range of errors was 0 to ?1.50 D.

DISCUSSION

Table

TABLECharacteristics of 19 Eyes of 15 Patients Undergoing Phakic Intraocular Lens Explantation and Cataract Surgery

TABLE

Characteristics of 19 Eyes of 15 Patients Undergoing Phakic Intraocular Lens Explantation and Cataract Surgery

The merits of intraoperative autorefraction compared with the other methods are ease, low cost, and reliability, even in eyes with previous corneal refractive surgery. Indeed, all of the other methods require true corneal power, which is calculated with difficulty after corneal surgery. The refractive data in the present study compare favorably with other series of PIOL explantation and cataract surgery.89 In the present study, the final mean spherical equivalent refraction of ?0.56 D can be partially explained by the goal of slightly undercorrecting when the exact PIOL power was unavailable.

Difficulties with intraoperative autorefraction may arise from poor active fixation (eg, macular degeneration, temporary loss of vision or motility due to peribulbar anesthesia, and microscope glare); therefore, the use of topical anesthesia is recommended, with possible augmentation by subconjunctival infiltration. Poor ocular motility can be easily overcome by aiming the autorefractor on the cornea and moving it slightly until patients recognize the fixation target.

The problem of effective lens position, which is not considered in aphakic autorefraction, is less relevant in high myopia because of the low-powered IOLs used. The effect of globe overinflation and underinflation on corneal curvature has been addressed by Ianchulev et al,6 who observed that in glaucoma no significant refractive change occurred and therefore only extreme hypotony or hypertony should be ruled out before autorefraction (for instance, by digital IOP evaluation). In the same study, it was anecdotally observed that ophthalmic viscosurgical material instead of BSS in the anterior chamber did not alter autorefraction.6 Finally, the effects of epithelial drying or of excess fluid on the cornea must be avoided, maintaining uniform hydration as described in the present study.

Intraoperative autorefraction provides a simple, inexpensive, and reliable method to calculate IOL power in myopic eyes in combined PIOL explantation and cataract surgery, with no need for preoperative data or complex calculations. In addition, it can be performed in eyes that have undergone excimer laser enhancement.

REFERENCES

1. Menezo JL, Peris -Martinez C, Cisneros-Lanuza AL, MartinezCosta R. Rate of cataract formation in 343 highly myopic eyes after implantation of three types of phakic intraocular lenses. J Refract Surg. 2004;20:317-324.

2. Alio JL, Abdelrahman AM, Javaloy J, Iradier MT, Ortuno V. Angle-supported anterior chamber phakic intraocular lens explantation causes and outcome. Ophthalmology. 2006;113:2213-2220.

3. Leccisotti A. Iridocyclitis associated with angle-supported phakic lenses. / Cataract Refract Surg. 2006;32:1007-1010.

4. Hoffer KJ. Biometry of 7,500 cataractous eyes. Am J Ophthalmol. 1980;90:360-368.

5. Hoffer KJ. Ultrasound axial length measurement in biphakic eyes. / Cataract Refract Surg. 2003;29:961-965.

6. lane hule ? T, Salz J, Hoffer K, Albini T, Hsu H, LaB ree L. Intraoperative optical refractive biometry for intraocular lens power estimation without axial length and keratometry measurements. / Cataract Refract Surg. 2005;31:1530-1536.

7. Leccisotti A. Intraoperative autorefraction in myopic lens exchange. Ophthalmology. 2 007;1 14:1030.

8. Alio JL, de la Hoz F, Ruiz-Moreno JM, Salem TF. Cataract surgery in highly myopic eyes corrected by phakic anterior chamber angle -supported lenses. / Cataract Refract Surg. 2000;26:13031311.

9. Morales AJ, Zadok D, Tard?o E, Anzoulatous G Jr, Litwak S, Mora R, Martinez E, Chayet AS. Outcome of simultaneous phakic implantable contact lens removal with cataract extraction and Pseudophakie intraocular lens implantation. / Cataract Refract Surg. 2006;32:595-598.

10. Pitault G, Leboeuf C, Leroux les Jardins S, Aue lin F, C hong - Sit D, Baudouin C. Biometrie optique des yeux avec implants phaques. JFr Ophtalmol. 2005;28:1052-1057.

11. el-Baha SM, el-Samadoni A, Idris HF, Rashad KM. Intraoperative biometry for intraocular lens (IOL) power calculation at silicone oil removal. Eur J Ophthalmol. 2003;13:622-626.

TABLE

Characteristics of 19 Eyes of 15 Patients Undergoing Phakic Intraocular Lens Explantation and Cataract Surgery

10.3928/1081-597X-20071101-11

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