Postoperative astigmatism induced by intraocular lens tilt

4. Ellingson IT: The uveitis-glaucoma-hyphema syndrome associated with the Mark VIII anterior chamber lens implant. Am Intra-Ocular Implant Soc J 4(2):50-53, 1978 5. Choyce DP: Complications of the AC implants of the early 1950's and the UGH or Ellingson syndrome of the late 1970's. Am Intra-Ocular Implant Soc J 4(2):22-29, 1978 6. Keates RH, Ehrlich DR: "Lenses of chance"; Complications of anterior chamber implants. Ophthalmology 85:408-414, 1978 7. Drews RC, Smith ME: Scanning electron microscopy of intraocular lenses. Ophthalmology 85:415-424, 1978 8. Siepser SB, Kline OR Jr: Scanning electron microscopy of removed intraocular lenses. Am Intra-Ocular Implant Soc J 9:176-183, 1983 9. Dersch MF: Comparative surface analysis of intraocular lenses. Am Intra-Ocular Implant Soc J 7:226-232, 1981 10. Mamalis N, Apple DJ, Brady SE, Notz RG, et al: Pathological and scanning electron microscopic evaluation of the 91Z intraocular lens. Am Intra-Ocular Implant Soc J 10:191-199, 1984 11. Clayman HM: Letters to the editor: Lifetime of polypropylene. Am Intra-Ocular Implant Soc J 9:458,1983 12. Girard LJ, Madero R, Monasterio R: Complications of the Simcoe flexible loop phacoprosthesis in the anterior chamber. Ophthalmic Surg 14:332-335, 1983 13. Lieppman ME: Letters to the editor: Loop precipitations in the 91Z lens. Am Intra-Ocular Implant Soc J 9:459, 1983 14. Wiley RG, Neville RG, Martin WG: Late postoperative hemorrhage following intracapsular cataract extraction with the IOLAB 91Z anterior chamber lens. Am Intra-Ocular Implant Soc J 9:466-469, 1983 15. Beehler CC: Letters to the editor: UGH syndrome with the 91Z lens. Am Intra-Ocular Implant Soc J 9:459, 1983 16. Terry AC, Stark WJ, Maumenee AE, Fagadau W: Neodymium-YAG laser for posterior capsulotomy. Am J Ophthalmol96:716-720, 1983 17. Tennant JL: Removal of intraocular lenses. Int Ophthalmol Glin 19(3):195-209, 1979

Postoperative astigmatism induced by intraocular lens tilt Alfred S. Jolson, M.D. Winter Park, Florida

Frank J. Seidl, M. D. Clearwater, Florida

ABSTRACT We report a case of intraocular lens implantation with an unexpected postoperative increase in spectacle astigmatism but no change in corneal astigmatism. The Nd: YAG laser was used to release a fibrous capsular band that was tilting the posterior chamber implant and causing four diopters of astigmatism. Key Words: capsular band, corneal astigmatism, lens tilt, spectacle astigmatism, YAG laser Tilting of an implanted intraocular lens (IOL) can cause astigmatism. If serial refractions of an implanted eye show a dramatic increase in astigmatism that cannot be explained by a change in keratometer readings, the implant may be tilted. We present a case in which the Nd:YAG laser was used to cut through a dense posterior capsular band that had tilted the posterior chamber implant vertically. CASE REPORT The patient, a 70-year-old male, had a visual acuity of 20/80 due to a posterior subcapsular cataract. His preoperative refraction and keratometer readings were -.25 + 3.25 x 170 and 49.50 horizontal/44.00vertical, respectively. A planned uncomplicated extracapsular cataract extraction was performed with the Cavitron irrigation-aspiration unit, and the posterior capsule was polished with the Kratz polisher. A +20 diopter, Coburn model 70, Sinskey-style posterior chamber lens was inserted and rotated 90° so the haptics were at approximately the 3-0' clock and 9-0'clock positions with the superior positioning hole at 12 o'clock. Two weeks postoperatively, the patient's visual acuity was 20/40 and the refraction was + 1.00 + 0.50 x 90. Six weeks postoperatively, the visual acuity was 20/200 and the refraction was -1.25 + 6.00 x 120. Examination showed a fibrous tissue band growing over the superior pole of the IOL with fibrous material coming from behind the lens through the 12-0'clock positioning hole and tilting the superior part of the lens posteriorly (Figure 1). Reprint requests to Alfred S. Jolson, M.D., 1850 Greenwich Avenue, Winter Park, Florida 32789.

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Fig. 1.

Golson) Pretreatment: A fibrous band attached at the superior pole of the IOL is tilting the implant posteriorly and creating astigmatism .

A synechiotomy to release the fibrous band was performed with 167 applications of the Meditec OPL-3 Nd:YAG mode-locked laser. The spot size was 45 microns, exposure time 30 picoseconds, and power 3. 7 millijoules. A week later a posterior capsulotomy was performed with 161 applications of the Meditec laser. After the final treatment the refraction was -.25 +2.00 x 180 with a visual acuity of20/40. There was no residual lens tilt (Figure 2). No significant post-laser pressure rise or iritis developed while the patient was on timolol (Timoptic®) 0 .5% b.i.d . and prednisolone acetate (Pred Forte®) 1.0% q.i.d. There was no vitritis or anterior displacement of the vitreous into the anterior chamber following the capsulotomy. Three months after laser therapy the refraction was -1.50 + 3.00 x 165 and one year after surgery the keratometry readings were 49.00/44.50.

Fig. 2. (Jolson) Post-treatment: Following Nd:YAG laser treatment the astigmatism has reduced and there is no lens tilt . 214

DISCUSSION Astigmatism is primarily corneal in origin, but can be caused by a tilted lens . Lenticular astigmatism can arise in the phakic patient, as with the subluxated lens occurring in Marfan's syndrome or trauma, or in the implant patient with a tilted IOL.I A dramatic change in spectacle astigmatism without a concomitant change in corneal astigmatism may be an early indication of lens tilt and implant position instability. Other causes of lens-induced astigmatism include an astigmatic error in the implant itself or iridodonesis and backward tilt from a sutured upper loop in iris-supported lenses. The induced astigmatism may be partially or completely neutralized by the corneal astigmatism .2 If the refractive change in astigmatism is caused by lens tilt, clinical observation of the degree of implant tilt should correspond to the calculated degree of tilt. In Table 1, the calculated degree of implant tilt is determined by finding the amount of induced astigmatism for the implant power in the vertical column and moving horizontally to the left to the tilt degrees column. 3 This patient had a tilt of approximately 25°. Table 1: Astigmatism induced at various degrees of lens tilt with various intraocular lens powers. Tilt Degrees 15°

Intraocular Lens Power (Diopters) 15

16

17

18

19

20

21

22

1.10

1.17

1.24

1.32

1.39

1.46

l.54

1.61

20°

2.06

2.20

2.34

2.48

2.26

2.75

2.89

3 .03

25°

3.47

3.70

3 9. 3

4.16

4.40

4.63

4.86

·5.09

30°

5.02

5. 35

5.69

6.02

6.36

6.69

7.03

7.36

35°

8.32

8.87

9.42

9.98 10.53 1l.09 11.64 12.20

Coincident with the excess lens-induced astigmatism is the change in corneal curvature during healing. The patient's cornea went from a preoperative againstthe-rule astigmatism (+3 .25 x 170) to an immediate postoperative with-the-rule astigmatism (+.50 x 90) because of tight sutures placed in the vertical meridian. With wound slippage (wound decay) the cornea returned to its original against-the-rule astigmatism (+3 .00 x 165) three months later. After cataract surgery, the cornea generally returns to its preoperative state (T. R. Mazzocco, M. D., Cataract, 1983, pp 11-12). REFERENCES l. Binkhorst RD: The cause of excessive as tigmatism with intraocular lens implants. Ophthalmology 86:672-674, 1979 2. Moore JG : Intraocular implants: The postoperative astigmatism. BrJ Ophthalmol 64:318-321, 1980 3. Borish 1M : Clinical Refraction, 3rd ed, Chicago, The Professional Press , Inc, 1970, p 1110

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