Endothelial changes following refractive surgery

Cyclodialysis cleft secondary to removal of an anterior chamber phakic intraocular lens

We present a patient who had decreased visual acuity and hypotony in the left eye 2 months after removal of an anterior chamber phakic intraocular lens (pIOL). Gonioscopy demonstrated a cyclodialysis cleft at the 6 o'clock position in the region of the IOL footplate, which was confirmed by ultrasound biomicroscopy. A cyclodialysis cleft formation is one possible complication of pIOL removal. Careful gonioscopy evaluation before removal of pIOLs should be mandatory to assess the amount of fibrosis and the presence of synechia between the IOL and the surrounding tissues.

Phakic Intraocular Lenses

An analytical review of the data available in the field of phakic intraocular lens implantation was conducted. Particular attention was paid to the more critical issues of intraocular lens sizing and safety guidelines. A comprehensive, competitive analysis of different implantation sites, intraocular lens model designs, and safety guidelines has been included. Specialized biometry techniques, such as very high frequency ultrasound and Scheimpflug imaging, have been reviewed, and a critical review of commercial claims regarding intraocular lens technologies has been included. Clinical studies of phakic intraocular lenses demonstrate increasing promise for the correction of refractive errors not amenable to mainstream excimer laser refractive surgery. The main issues currently revolve around adequate lens design (VHF ultrasound study suggests that custom-design and sizing may be the most effective and safest approach for every phakic IOL model), because these devices will be required to remain physiologically inert and anatomically compatible with internal ocular structures and relations for several decades. The possibility of safe removing or exchanging the IOL should remain a feasible option over time. It is of utmost importance that we continue to critically evaluate current encouraging short-term outcomes, which are being extrapolated to the longer term by ongoing high resolution imaging and monitoring of the anatomical and functional relations of implanted phakic IOLs.

Corneal endothelial specular microscopy following deep lamellar keratoplasty with lyophilised tissue

PURPOSE

To assess the corneal endothelial cell density following deep lamellar keratoplasty (DLK) carried out by air dissection and with the transplantation of lyophilised tissue.

METHOD

Contact endothelial specular microscopy was carried out on a series of patients who had undergone DLK with a minimum of 1 year post-operative follow-up.

RESULTS

Twenty eyes of 18 patients were examined at follow-up times ranging from 1 to 8 years post-operatively (mean 3 years). Indications for surgery were: keratoconus (n = 12), herpes simplex virus (HSV) keratitis (n = 1), herpes zoster ophthalmicus (HZO) keratitis (n = 1), lipid keratopathy (n = 2), lattice dystrophy (n = 1) and corneal scarring (n = 3). Overall, mean post-operative cell density was 2417 cells/mm2 (range 928-3656 cells/mm2). In eyes with pathological conditions not likely to have affected the endothelial cell density, such as keratoconus or lattice degeneration, the mean cell density was 2837 cells/mm2 (range 1030-3656 cells/mm2).

CONCLUSIONS

In patients undergoing DLK for conditions such as keratoconus the post-operative cell density was at a normal level in the majority of cases. Cell loss through this surgical intervention thus appears generally to be small. The prospect for long-term survival of these grafts is good.

Laser in situ keratomileusis for moderate and high myopia and myopic astigmatism

OBJECTIVE

This study evaluated the predictability, stability, and safety of laser in situ keratomileusis (LASIK) in myopia and myopic astigmatism.

DESIGN

The study design was a prospective, unmasked, nonrandomized clinical trial.

PARTICIPANTS

Participating were 25 patients with myopia (37 eyes) with astigmatism of less than 1.00 diopter (D), divided into 3 subgroups (-5.00 to -9.90 D, 8 eyes; -10.00 to -14.90 D, 10 eyes; -15.00 to -29.00 D, 19 eyes), and 37 patients with myopia (56 eyes) with corneal astigmatism of 1.00 to 4.50 D, divided into 3 subgroups (-5.00 to -9.90 D, 12 eyes; -10.00 to -14.90 D, 24 eyes; -15.00 to -29.00 D, 20 eyes).

INTERVENTION

LASIK was performed using the Automatic Corneal Shaper and the Keracor 116 excimer laser.

MAIN OUTCOME MEASURES

Visual acuity, manifest refraction, central corneal islands, ablation decentration, and patient satisfaction were measured.

RESULTS

At 12 months, predictability, regression between 1 and 12 months, uncorrected visual acuity (UCVA), loss of two or more lines of corrected visual acuity, and patient satisfaction of the spherical (toric) groups are reported. Subgroups -5.00 to -9.90 D: 100% (75%) +1.00 D; regression less than or equal to 1.00 D in 100% (91.7%); UCVA greater than or equal to 20/40 in 87.5% (70%); none lost two or more lines; 100% (84%) highly satisfied. Subgroups -10.00 to -14.90 D: 60% (78.3%) +/-1.00 D; regression less than or equal to 1.00 D in 100% (87%); UCVA greater than or equal to 20/40 in 77.8% (86.4%); 10% (4.3%) lost two lines; 90% (91%) highly satisfied. Subgroups -15.00 to -29.00 D: 38.9% (21.4%) +/-1.00 D; regression less than or equal to 1.00 D in 72.2% (64.3%); UCVA greater than or equal to 20/40 in 33.3% (40%); 5.6% (7.1%) lost two lines; 78% (50%) highly satisfied. Differences of predictability and change of manifest refraction between subgroups of -5.00 to -9.90 D and -15.00 to -29.00 D were statistically significant. Central islands (decentrations) were observed in 17% (5.6%) of eyes of the spherical and in 16% (4.1%) of the toric group. Overall, the corneal interface was visible in 8.2%.

CONCLUSIONS

The LASIK method used in this study showed stability of manifest refraction and adequate uncorrected central visual acuity in a large percentage of patients with myopia up to -15.00 D. Corneal stability was not as uniform. Central corneal islands were observed in a sizable minority of patients despite pretreatment. For myopia greater than 15.00 D, accuracy and patient satisfaction were sufficiently poor to advise against using the authors' treatment technique in these groups. Visually significant microkeratome and laser-related problems were noted in a smaller percentage of patients. Patients with astigmatism correction were less pleased with results than were patients who received spherical corrections.