The effect of riboflavin-ultraviolet A-induced collagen cross-linking on intraocular pressure measurement: an experimental study

PURPOSE

To investigate the effect of corneal collagen cross-linking (CCL) on tonopen measurements of intraocular pressure (IOP).

METHODS

CCL with 0.1% riboflavin solution and 30 min of ultraviolet A radiation was performed on the right eye of 15 New Zealand albino adult rabbits (1.8-2.4 kg) (15 eyes). The left eye served as control. IOP was measured by a pressure transducer system (true IOP) and by the tonopen hand-held device (corneal applanation tonometer) before treatment, at 1 week, 1 month and 3 months following CCL. Reference pressure in the globe was increased by increments of 10 mm Hg from 10 to 40 mm Hg, using an anterior chamber infusion on a stand with variable height, and tonopen IOP measurements were recorded for each reference pressure in both eyes.

RESULTS

Before CCL, tonopen readings were similar between the two eyes (p>0.05). Tonopen underestimated the true IOP in all cases. Following CCL treatment, IOP measurements were significantly higher in the treated eye, at all time intervals (0.005<p<0.03). The most significant difference between true and measured IOP was noted at a reference pressure of 20 mm Hg.

CONCLUSIONS

IOP measurements following CCL are overestimated by the tonopen, probably due to increased stiffness of the treated cornea.

Cataract Extraction and Toric Intraocular Lens Implantation for the Management of Pellucid Marginal Degeneration and Cataract

We report cataract surgery with toric intraocular lens implantation for the management of senile cataract combined with pellucid marginal degeneration. A 72-year-old man with bilateral senile cataract and significant against-the-rule astigmatism sought counseling for blurry vision and glare, mostly in the right eye. Based on ophthalmic examination and corneal topography, a diagnosis of pellucid marginal degeneration and cataract was made. Since visual acuity and refraction had been stable in the past 3 years, the patient underwent cataract extraction and implantation of a custom-designed toric posterior chamber intraocular lens. Postoperative follow-up of 1.5-year demons- trated marked improvement in visual acuity, stable refraction and patient satisfaction. This treatment for pellucid marginal degeneration offers the simplicity of regular cataract surgery, and avoids the known complications of keratoplasty and other corneal surgical manipulation for the management of pellucid marginal degeneration.

How to cite this article

Bahar I, Bialer O. Cataract Extraction and Toric Intraocular Lens Implantation for the Management of Pellucid Marginal Degeneration and Cataract. Int J Keratoco Ectatic Corneal Dis 2012;1(1):66-67.

Femtosecond LASIK combined with astigmatic keratotomy for the correction of refractive errors after penetrating keratoplasty

BACKGROUND AND OBJECTIVE

To evaluate the outcomes of femtosecond laser in situ keratomileusis (LASIK) compared to combined LASIK and astigmatic keratotomy in the treatment of refractive errors following penetrating keratoplasty.

PATIENTS AND METHODS

A retrospective review was performed on 18 eyes of 16 patients who underwent LASIK for visual rehabilitation after penetrating keratoplasty. Seven eyes (38.8%) had undergone paired relaxing incisions with topographic guidance prior to LASIK performance.

RESULTS

Preoperative uncorrected visual acuity was 20/100 or worse in 13 eyes (72.2%) and best-corrected visual acuity (BCVA) was 20/40 or better in 15 eyes (83.3%). After LASIK, uncorrected visual acuity was 20/40 or better in 10 eyes (55.5%) and BCVA was 20/40 or better in 17 eyes (94.4%). Three eyes (16.6%) had a loss of 1 to 2 lines of BCVA. No difference in visual outcomes was noted in eyes undergoing LASIK and astigmatic keratotomy versus LASIK alone. An increased complication rate was noted in patients who also underwent astigmatic keratotomy and was associated with flap creation.

CONCLUSION

Femtosecond LASIK is effective in reducing ametropia after penetrating keratoplasty. Astigmatic keratotomy might complicate flap creation in LASIK; therefore, photorefractive keratectomy should be considered for patients who had previous astigmatic keratotomy to reduce astigmatism.

Effect of Dexamethasone Eyedrops on Blood Glucose Profile

PURPOSE

To evaluate the effect of dexamethasone eyedrops on blood glucose.

METHODS

Two hundred eighty-five patients who underwent cataract surgery were prospectively randomized to receive treatment with topical dexamethasone or diclofenac for 1 month. A capillary blood sample was collected before surgery, immediately after, 1 week later, and 1 month later.

RESULTS

A significant increase in blood glucose levels was noted only in the diabetic dexamethasone group, from 170 +/- 55.5 (mg/dl) before surgery to 229 +/- 76.8 (mg/dl) 1 month later (p = 0.05, 95% confidence interval of -13 to -83.2). The latter level was significantly higher than the 1-month level in the diabetic patients treated with diclofenac drops (198.4 +/- 66.5 mg/dl, p = 0.038).

CONCLUSIONS

Postoperative dexamethasone eyedrops have a greater effect on the blood glucose profile of diabetic patients than on nondiabetic patients. Clinicians should be alerted to this risk and may initiate appropriate follow-up in this patient subgroup.

Fibrin Glue versus Vicryl Sutures for Primary Conjunctival Closure in Pterygium Surgery: Long-Term Results

PURPOSE

To compare the long-term results of conjunctival closure with fibrin adhesive or Vicryl sutures in pterygium surgery.

METHODS

The study was performed in 81 patients (81 eyes) with primary nasal pterygium. Surgery in all patients consisted of the bare sclera technique combined with intraoperative administration of mitomycin C 0.02%. Patients were randomized to undergo conjunctival closure with a fibrin adhesive (Quixil) (n = 42) or Vicryl sutures (n = 39). Clinical assessment was performed on postoperative days 1, 3, 10, and 21 and thereafter at 3, 6, and 12 months. All patients completed a questionnaire at each follow-up visit grading pain, discomfort, and satisfaction with the procedure. The groups were compared for operative time, ocular signs and symptoms, overall satisfaction, and recurrence rate.

RESULTS

Average operative time was 16 min in the fibrin-glue group and 28 minutes in the Vicryl-suture group (p < 0.05). Significantly less pain and discomfort were noted in the subjects treated with glue than in controls (p < 0.05). Satisfaction was significantly higher in the study group (p < 0.04). There were no complications during follow-up period in the glue-treated patients; one patient in the suture group had a medically treatable corneal dellen. At the end of follow-up, recurrent pterygium developed in five (11.9%) eyes of the fibrin-glue group and in three (7.7%) eyes of the Vicryl-suture group (p < 0.05).

CONCLUSIONS

The use of fibrin glue in pterygium surgery significantly reduces operative time and patient pain compared with suturing. However, it may be associated with a higher recurrence rate.

Fibrin Glue as a Suture Substitute: Histological Evaluation of Trabeculectomy in Rabbit Eyes

PURPOSE

To describe the outcome of the use of fibrin adhesive (Quixil) in penetrating trabeculectomy in a rabbit model.

METHODS

Fibrin adhesive was used experimentally to attach the conjunctiva and the scleral flap in two groups of 17 New Zealand albino adult rabbits (34 eyes). In the first experiment (20 eyes), the fibrin adhesive was used to reattach the tissue after conjunctival peritomy and scleral flap only in 14 eyes (experiment I). In 6 eyes (controls), the conjunctiva was attached with nylon sutures. In the second experiment (14 eyes), the fibrin adhesive was used after conjunctival peritomy, scleral flap, and penetrating trabeculectomy in 8 eyes (experiment II). In a control group of 6 eyes, nylon sutures were used to attach the scleral flap and the conjunctiva after penetrating trabeculectomy. Biomicroscopy and histopathological examinations were performed on postoperative days 1, 3, 7, 14, 21, and 30. Intraocular pressure was measured before and after surgery in the second experiment. Main outcome measures are histological presence of adhesive in the tissue, degree of capillary congestion, inflammatory reaction, collagen density [scar formation] and clinical (IOP measurements before and after surgery, conjunctival chemosis, anterior chamber reaction, presence of filtering bleb and wound leakage).

RESULTS

In experiments I and II, the adhesive was well identified histologically in the tissue as an amorphic eosinophilic substance for up to day 3 and nearly disappeared by day 7. An acute inflammatory reaction was noted for up to 14 days, which converted to chronic inflammation with collagen deposits and scar formation by day 30. Similar inflammatory reaction was observed in the control group. The adhesive had no adverse effects on ocular tissue compared with sutures. One eye in experiment II demonstrated wound dehiscence. Intraocular pressure dropped from 17.35 mmHg preoperatively to 8.28 mmHg on postoperative day 1 in experiment II, and from 17.2 mmHg to 11.5 mmHg in the controls. No significant change in intraocular pressure was noted in experiment I.

CONCLUSIONS

The fibrin adhesive had no adverse effects on ocular tissue compared with sutures. It might serve as an effective substitute for conjunctival and scleral wound closure in trabeculectomy surgery.

Busin Guide vs Forceps for the Insertion of the Donor Lenticule in Descemet Stripping Automated Endothelial Keratoplasty

PURPOSE

To compare two insertion methods in Descemet stripping automated endothelial keratoplasty (DSAEK): Busin guide-assisted vs Forceps-assisted insertion of the corneal lenticule graft.

DESIGN

Prospective, consecutive, comparative, nonrandomized study.

METHODS

setting: Cornea clinic at the Toronto Western Hospital. study population: Sixty-three eyes of 63 consecutive patients were included. All patients underwent DSAEK for Fuchs endothelial dystrophy, pseudophakic bullous keratopathy, aphakic bullous keratopathy, failed graft, or iridocorneo endothelial syndrome. Twenty-six consecutive donor discs were inserted with the Busin guide and 37 consecutive eyes underwent forceps assisted insertion of the donor. main outcome measures: Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, corneal endothelial cell loss, and postoperative complications.

RESULTS

Busin guide-assisted DSAEK group had significantly worse UCVA and lower donor endothelial cell counts preoperatively. No significant differences were noted in the intraoperative or postoperative complications. Six months following surgery, BCVA was not significantly different between groups: 20/37 in the Busin guide-assisted DASEK group vs 20/42 in the Forceps-assisted group (P = .39). Mean spherical equivalent was -0.02 diopters (D) and 0.82 D (P = .06), and mean refractive cylinder was 2.2 D and 1.31 D (P = .0006), respectively. Endothelial cell loss was significantly lower in the Busin guide-assisted DASEK group: 25% loss vs 34.3% loss in the Forceps-assisted DSAEK group. (P = .04).

CONCLUSIONS

Although visual outcomes were not different between the groups studied, Busin guide-assisted DSAEK resulted in lower percentage of endothelial cell loss compared with forceps insertion, six months following surgery.

Comparison of three different techniques of corneal transplantation for keratoconus

PURPOSE

To compare the visual outcomes following deep anterior lamellar keratoplasty (DALK), penetrating keratoplasty (PK), and manual top-hat PK (TH-PK) in subjects undergoing corneal transplantation for keratoconus (KC).

DESIGN

A retrospective comparative case series.

METHODS

settings: Cornea clinic at the Toronto Western Hospital. study population: Fifty patients who underwent corneal transplantation for KC: 17 eyes underwent DALK, 20 eyes underwent traditional PK, and 13 had TH-PK. main outcome measures: Preoperative and postoperative uncorrected and best spectacle-corrected visual acuity (UCVA, BSCVA), high-order aberrations (HOA), complication rate, and endothelial cell counts.

RESULTS

The median BSCVA at 12 months follow-up was 20/40 in the DALK eyes and 20/30 in the traditional PK and TH-PK eyes. The mean final spherical equivalent power in the three groups was less than -1 diopter (D). The median astigmatism was less than 3.5 D in the three groups. Complication rates were similar for three groups, although the DALK group tended toward more complications. Although DALK and TH-PK procedure results in significantly shorter time to suture removal (P < .01), they caused increased levels of HOAs (P = .02). Endothelial cell counts at 12 months were significantly higher in DALK and TH-PK eyes when compared to the traditional PK eyes (P < .001).

CONCLUSIONS

DALK, PK, and TH-PK provide comparable visual outcomes in keratoconus patients. Although DALK and TH-PK induce more HOA, they speed up the time to suture removal and provide higher endothelial cell density at one year of follow-up.

IntraLase-enabled astigmatic keratotomy for postkeratoplasty astigmatism

PURPOSE

To report on the outcomes of IntraLase-enabled astigmatic keratotomy (IEAK) and to compare it with manual astigmatic keratotomy (AK) for the management of postkeratoplasty astigmatism.

DESIGN

Retrospective, comparative case series.

METHODS

Forty eyes of 39 patients treated at a cornea clinic at the Toronto Western Hospital were included. Twenty eyes underwent manual AK and 20 eyes underwent IEAK. The main outcome measures included preoperative and postoperative manifest refraction, uncorrected and best-corrected visual acuity (UCVA, BCVA), corneal topography, high-order ocular aberrations, and complications.

RESULTS

In the manual AK group, UCVA (logarithm of the minimum angle of resolution) improved from 1.08 +/- 0.29 before surgery to 0.93 +/- 0.45 after surgery (P = .09), and in the IEAK group, UCVA improved from 1.14 +/- 0.42 before surgery to 0.82 +/- 0.44 after the procedure (P = .004). BCVA improved from 0.63 +/- 0.40 to 0.44 +/- 0.38 (manual AK; P = .16) and from 0.52 +/- 0.38 to 0.29 +/- 0.26 (IEAK; P = .01), respectively. Mean cylinder reduction was 3.23 +/- 4.69 diopters in the manual AK group and 4.26 +/- 1.72 diopters in the IEAK group (P = .36). Two eyes in each group lost one line of BCVA. Three patients (15%) in the manual AK group had corneal perforation and required resuturing of the AK wound (P = .23) Overcorrection occurred at a similar rate in the two groups.

CONCLUSIONS

Treatment of postkeratoplasty astigmatism with IntraLase is a safe and effective surgical procedure and resulted in a significant improvement in UCVA and BCVA compared with manual AK. A larger sample series is needed to refine further this new technique of AK and to compare it with accepted manual techniques.