Charalambos S. Siganos

Induced optical aberrations following formation of a laser in situ keratomileusis flap

Purpose: To determine how refractive error, visual acuity, and high‐order aberrations (3rd‐ and 4th‐order) are affected by the formation of a lamellar corneal flap during laser in situ keratomileusis (LASIK). Setting: University refractive surgery center. Methods: The effect of lamellar corneal flap formation was analyzed in 15 myopic eyes (mean preoperative refraction −4.72 diopters [D] [range −1.25 to −7.25 D]). The flap was created using a 2‐step procedure: (1) a nasally hinged lamellar corneal flap was created; (2) the flap was lifted and stromal ablation performed 2 months after the flap was made. A Hartmann‐Shack aberrometer was used to measure the aberrations. Results: There was no significant change in the refractive error (spherical equivalent pre‐flap −4.72 ± 1.99 D and post‐flap −4.62 ± 1.99 D [P = .28]) or visual acuity (pre‐flap uncorrected visual acuity [UCVA] 0.07 and best corrected visual acuity [BCVA] 0.96; post‐flap UCVA 0.08 and BCVA 0.95 [P = .16 and P = .33, respectively]). A statistically significant increase in total higher‐order wavefront aberrations was observed following flap formation (root mean square pre‐flap 0.344 ± 0.125 and post‐flap 0.440 ± 0.221 [P = .04]). Conclusion: Flap formation during LASIK can modify the eyes existing natural higher‐order aberrations (especially spherical and coma‐like aberrations along the axis of the flaps hinge), while visual acuity and refractive error remain unaffected.

Management of keratoconus with Intacs

PURPOSE To prospectively study the effects of the use of Intacs microthin prescription inserts for the management of keratoconus. DESIGN Prospective nonrandomized clinical trial. METHODS Thirty-three eyes of 26 keratoconus patients (17 males and 9 females) ages 21 to 51 years (mean age, 32 +/- 9.7 years) were included in the current study. All patients had clear central corneas and contact lens intolerance. Patients were excluded if any of the following criteria applied after the preoperative examination: previous intraocular or corneal surgery; history of herpes keratitis; diagnosed autoimmune disease; and systemic connective tissue disease. Two Intacs segments of 0.45-mm thickness were inserted in the cornea of each eye, aiming at embracing the keratoconus area to try to achieve maximal flattening. Preoperative examination included uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, keratometric data, and corneal topography. RESULTS Intacs were successfully implanted in all eyes. In one eye Intacs were removed after 3 months because of their improper (superficial) placement. The follow-up ranged from 1 to 24 months (mean: 11.3 months). The mean UCVA significantly improved from 0.13 +/- 0.14 (range, counting fingers [CF]-0.5) to 0.39 +/- 0.27 (range, CF-1.0) (P <.01). Of 33 eyes, 2 eyes lost 1 line of UCVA, and 3 eyes maintained the preoperative UCVA, whereas the rest (28 eyes) experienced a 1- to 10-line gain. The mean BCVA also improved from 0.47 +/- 0.31 (range, CF-1.0) to 0.64 +/- 0.26 (range, 0.1-1.0) (P <.01). Of 33 eyes, 4 eyes experienced 1- to 2-line loss of BCVA, 4 eyes maintained the preoperative BCVA, whereas the rest (25 eyes), experienced a 1- to 6-line gain. Of 3 patients (3 eyes) with unsatisfactory results, 1 patient improved with one segment removal and in 2 patients the segments were permanently removed. One of these eyes underwent successful PKP. CONCLUSIONS With mean follow-up of 11.3 months, intracorneal ring segments implantation improved UCVA and BCVA in the majority of the keratoconus patients. Even though the results are encouraging, concern still exists regarding the predictability as well as the long-term effect of such an approach for the management of keratoconus.

Intraoperative Application of Topical Mitomycin C for Pterygium Surgery

BACKGROUND Postoperative recurrence of pterygium occurs in many patients. The authors studied the recurrence rate of pterygium after administration of a single intraoperative dosage of topcial mitomycin C at the completion of pterygium excision. METHODS AND PATIENTS Eighty-one patients underwent excision of the pterygium, leaving the sclera bare. The first 60 patients were randomized into two treatment groups of 30 patients each. Their remaining 21 patients were offered mitomycin C. Group 1 included 49 patients (30 randomized and 19 of the remaining 21 patients) who received an intraoperative application of 0.02% (0.2 mg/ml) mitomycin C for 5 minutes, and group 2 included 32 patients (30 randomized and 2 of the remaining 21 patients) who received NaCl 0.9% instead of mitomycin C. Patients were followed from 12 to 28 months in a masked manner. RESULTS The pterygium recurred in 2 (4%) of 49 patients in group 1 and in 15 (46.7%) of the 32 patients in group 2 (P = 0.0001). A delay of epithelialization for 5 and 10 weeks occurred in two patients in group 2 and granuloma manifested in one patient in group 1. CONCLUSION This study indicates that intraoperative administration of a single dosage of 0.02% mitomycin C is an effective treatment for prevention of recurrence of pterygium.

Management of corneal ectasia after laser in situ keratomileusis with INTACS.

PURPOSE To evaluate the safety and efficacy of intrastromal corneal ring segments (ICRS, INTACS, Keravision) for the correction of corneal ectasia after laser in situ keratomileusis (LASIK). METHODS In this prospective, noncomparative case series, INTACS were implanted in three eyes (two patients) that were ectatic after LASIK. Mean follow-up was 8.7 months (range, 8 to 10 mo). RESULTS No intraoperative complications occurred. After INTACS implantation, uncorrected visual acuity ranged from 20/20 to 20/25 at 6 months and remained stable until 9 months. Mean postoperative spherical equivalent refraction was 0.50 D at 1 month and no significant changes appeared up to 9 months after INTACS implantation. After INTACS implantation, no eye lost any lines of Snellen spectacle-corrected visual acuity and two eyes gained from one to two lines. There was an increase in topographical regularity in all three eyes. CONCLUSION Implantation of INTACS in eyes with corneal ectasia after LASIK resulted in good refractive outcome, absence of complications, and improvement in visual acuity.

Complications of intrastromal corneal ring segment implantation using a femtosecond laser for channel creation: a survey of 850 eyes with keratoconus

Acta Ophthalmol. 2011: 89: 54–57

Iontophoresis–gentamicin delivery into the rabbit cornea, using a hydrogel delivery probe

PURPOSE To evaluate the efficacy of penetration of gentamicin into the cornea of rabbits using iontophoresis with a hydrogel-gentamicin containing probe. METHODS Eight of 10 groups (groups 3-10) of 6 rabbits (one eye per rabbit), underwent corneal iontophoresis using soft stable hydroxyethyl methacrylate hydrogel discs (80% water content) loaded with gentamicin sulphate which were mounted on an iontophoresis probe. The studied current intensities were 0, 0.1, 0.3 and 0.6 mAmp, and the durations of iontophoresis were 10 and 60 sec. Two control groups received 1.4% topical drops of gentamicin every 5 min for 1 hr (group 1) or sub-conjunctival injection of 10 mg gentamicin (group 2). Following sacrifice, aqueous humour was taken, corneas were excised, and gentamicin concentration was determined in aqueous humour and cornea samples. RESULTS Post-iontophoresis, the concentration of gentamicin in the corneas ranged from high (88.60 +/- 38.64 microg ml(-1)) to very low (0.10 +/- 0.89 microg ml(-1)). Both the control groups and those rabbits treated with current intensity of 0.1 mAmp or greater obtained therapeutic gentamicin levels in the corneas. Use of iontophoresis for 60 sec or current intensity greater than 0.1 mAmp obtained corneal gentamicin levels not different from sub-conjunctival injection. Application of current intensity of 0.1 mAmp or greater gave corneal gentamicin concentrations comparable to topical application of the drug, except when 0.6 mAmp were used for 60 sec (p = 0.05). Increasing current intensity or duration of iontophoresis significantly increased (p = 0.001 for both) gentamicin penetration into the cornea. Current intensity had more influence (Beta2 = 0.40) than duration (Beta2 = 0.13) on drug penetration. A significant interaction was found between the duration of iontophoresis and the current intensity. Very small or no concentrations of the drug were discovered in the anterior chambers of rabbits. CONCLUSIONS Iontophoresis using hydrogel-gentamicin probe may deliver therapeutic concentrations of gentamicin into the cornea.

Treatment of chronic dry eye: focus on cyclosporine

To review the current treatment of chronic dry eye syndrome, focusing on cyclosporine A (CsA), a systematic literature search was performed using PubMed databases in two steps. The first step was oriented to articles published for dry eye. The second step was focused on the use of CsA in dry eye. A manual literature search was also undertaken based on citations in the published articles. The knowledge on the pathogenesis of dry eye syndrome has changed dramatically during the last few years. Inflammation and the interruption of the inflammatory cascade seem to be the main focus of the ophthalmologic community in the treatment of dry eye, giving the anti-inflammatory therapy a new critical role. The infiltration of T-cells in the conjuctiva tissue and the presence of cytokines and proteasis in the tear fluid were the main reason introducing the use of immunomodulator agents such as corticosteroids, cyclosporine, and doxycicline in order to treat dry eye syndrome. CsA emulsion is approved by the FDA for the treatment of dry eye, while clinical trials of this agent have demonstrated efficacy and safety of CsA. CsA seems to be a promising treatment against dry eye disease. New agents focused on the inflammatory pathogenesis of this syndrome in combination with CsA may be the future in the quest of treating dry eye. More studies are needed to determine the efficacy, safety, timing, and relative cost/effect of CsA.

The intraoperative use of mitomycin-C in excision of ocular surface neoplasia with or without limbal autograft transplantation.

Purpose. To evaluate the efficacy of intraoperative mitomycin-C in excision of ocular surface neoplasia for prevention of recurrence. Methods. Seven patients (eight eyes), three men and four women, aged 56 to 87 years (mean, 73.8 years), with lesions suspicious for corneal or conjunctival neoplasia, were operated on between October 1998 and March 2000. During excision of the lesion, mitomycin-C 0.02% was applied intraoperatively for 5 minutes. In two cases, excision was combined with conjunctival limbal autograft transplantation. All excised lesions were sent for histopathologic evaluation. Results. During the follow-up period ranging from 6 to 28 months (mean, 16 months) one patient (one eye) died of an unrelated cause. Histopathologic study showed four cases of squamous cell carcinoma, one case of carcinoma in situ, two cases of dysplasia, and one case of actinic keratosis. Of the eight eyes, no clinical recurrence of the lesion occurred in seven eyes, whereas one eye with squamous cell carcinoma showed mild recurrence 5 months after surgery and was successfully treated with topical mitomycin-C. Up to the last follow-up of this case 10 months later, the lesion did not recur. Conclusion. The excision of conjunctival and corneal epithelial neoplasia combined with the intraoperative use of mitomycin-C seems to reduce the recurrence rate. The combined use of mitomycin-C and conjunctival limbal autograft transplantation in two cases did not alter the surgical outcome. More cases and a longer follow-up are needed to establish the efficacy of such an approach.

Intacs for early pellucid marginal degeneration

A 42-year-old man had Intacs (Addition Technology Inc.) implantation for early pellucid marginal degeneration (PMD). Two Intacs segments (0.45 mm thickness) were inserted uneventfully in the fashion typically used for low myopia correction (nasal-temporal). Eleven months after the procedure, the uncorrected visual acuity was 20/200, compared with counting fingers preoperatively, while the best spectacle-corrected visual acuity improved to 20/25 from 20/50. Corneal topographic pattern also improved. Although the results are encouraging, concern still exists regarding the long-term effect of this approach for the management of patients with PMD.

Hemorrhagic Descemet's membrane detachment as a complication of deep sclerectomy: a case report.

PurposeTo report a case that developed hemorrhagic Descemets membrane detachment after deep sclerectomy. Patient and MethodsCase report. A 63-year-old diabetic patient suffering from uncontrolled chronic open-angle glaucoma with full medication, underwent an uneventful deep sclerectomy operation combined with intraoperative Mitomycin-C. ResultsOn the second postoperative day, a hemorrhagic Descemets membrane detachment (HDDM) was observed. The hemorrhage showed rapid absorption rate during the first two weeks along with reduction of the HDDM. After this period of time the rate of blood absorption was decreased. The Descemets membrane reattached completely six months after surgery without any intervention but a paracentral corneal scar was present. The bleb was not functionally impaired during the whole postoperative period, and intraocular pressure remained stable at the level between 12 and 15 mmHg without medication. ConclusionHemorrhagic Descemets membrane detachment should be considered as a potential complication of deep sclerectomy.