Risk of induction of corneal neovascularization with topical erythropoietin: an animal safety study

Purpose: To evaluate the pro-angiogenic effect of topical erythropoietin on cornea in chemical burn-injured rabbit eyes. Methods: The corneal alkali-burn injury was induced in 10 eyes of 10 rabbits using filter paper saturated with 1.0 mol sodium hydroxide. The eyes were categorized into the treatment group (n = 5) that received topical erythropoietin (3000 IU/mL) every 8 hr for one month versus the control group (n = 5) that received normal saline every 8 hr for one month. All eyes were treated with topical ciprofloxacin every 8 hr until corneal re-epithelialization was complete. Corneal epithelial defects, stromal opacity, and neovascularization were evaluated after the injury. At the conclusion of the study, the rabbits were euthanized and their corneas were submitted to histopathological examination. Results: Baseline characteristics including the rabbits' weight and the severity of corneal injury were comparable in two groups. Time to complete corneal re-epithelialization was 37 days in the treatment group and 45 days in the control group (P = 0.83). There was no significant difference between the groups in the rate of epithelial healing or corneal opacification. Clinical and microscopic corneal neovascularization was observed in one eye (20%) in the treatment group and two eyes (40%) in the control group (P = 0.49). Conclusion: Recombinant human erythropoietin administered topically did not induce vessel formation in rabbit corneas after chemical burn.

Traumatic wound dehiscence following corneal transplantation

To investigate the incidence, mechanisms, characteristics, and visual outcomes of traumatic wound dehiscence following keratoplasty. Medical records of 32 consecutive patients with traumatic globe rupture following keratoplasty who had been treated at our center from 2001 to 2009 were retrospectively reviewed. The study population consisted of 32 eyes of 32 patients including 25 men and 7 women with history of corneal transplantation who had sustained eye trauma leading to globe rupture. Mean patient age was 38.1 [range, 8 to 87] years and median interval between keratoplasty and the traumatic event was 9 months [range, 30 days to 20 years]. Associated anterior segment findings included iris prolapse in 71.9%, lens extrusion in 34.4%, and hyphema in 40.6% of eyes. Posterior segment complications included vitreous prolapse [56%], vitreous hemorrhage [28%] and retinal detachment [18%]. Eyes which had undergone deep anterior lamellar keratoplasty [DALK; 5 cases, 15.6%] tended to have less severe presentation and better final visual acuity. There was no correlation between the time interval from keratoplasty to the traumatic event, and final visual outcomes. The host-graft interface demonstrates decreased stability long after surgery and the visual prognosis of traumatic wound dehiscence is poor in many cases. An intact Descemet's membrane in DALK may mitigate the severity of ocular injuries, but even in these cases, the visual outcome of globe rupture is not good and prevention of ocular trauma should be emphasized to all patients undergoing any kind of keratoplasty.

Intraocular lens power calculation after corneal refractive surgery

Purpose: To report refractive outcomes following phacoemulsification [PE] and posterior chamber intraocular lens [PCIOL] implantation in eyes with previous corneal refractive surgery

Methods: In this retrospective comparative study, 18 consecutive eyes of 14 patients with previous keratorefractive surgery for myopia including photorefractive keratectomy [PRK, 6 eyes; 33.3%] and laser in situ keratomileusis [LASIK, 12 eyes; 66.7%] underwent PE+PCIOL. Computerized corneal topography was employed to determine the flattest keratometric reading within the 3-mm central zone. This value was inserted into the Sanders-Retzlaff-Kraff/T [SRK/T] formula to calculate IOL power. IOL power selected for implantation was 1 D greater than the calculated value described above

Results: Mean age and follow-up period were 54.1 +/- 11.5 years and 29.9 +/- 26.3 months, respectively. Mean implanted lens power was 18.56 +/- 3.86 D which was not significantly different from mean back-calculated IOL power for target refraction [19.04 +/- 4.16 D] [P=0.28]. There was no significant difference between mean target refraction [-0.94 +/- 0.52 D] and achieved postoperative spherical equivalent refractive error [-0.62 +/- 1.06] at final follow-up [P=0.28]. The achieved spherical equivalent refractive error was within +/- 0.50 D of intended refraction in 8 [44.4%] eyes, within +/- 1.0 D in 11 [61.1%] eyes, and within +/- 2.0 D in 16 [88.9%] eyes. In a subgroup of patients [5 eyes] with complete pre-refractive surgery data, the difference between post-refractive surgery keratometry method and all other methods [P=0.02] and between the current method and the Feiz-Mannis method [P=0.01] was statistically significant

Conclusion: The method suggested herein is simple and independent of pre-refractive surgery data with results comparable to other commonly used methods

Changing indications and surgical techniques for corneal transplantation between 2004 and 2009 at a tertiary referral center

The aim of this study is to report the indications, techniques, and clinical outcomes of corneal transplantation and investigate any changing trends in surgical techniques over a 6 year period. Records of patients who had undergone any kind of corneal transplantation at Labbafinejad Medical Center, Tehran, Iran, from January 2004 to December 2009 were reviewed to determine the indications and types of corneal transplantation. Postoperative best-corrected visual acuity, refractive error, graft clarity, and complications were reported. During this period, 1859 eyes of 1624 patients with a mean age of 41.3 +/- 21.3 years underwent corneal transplantation. The most common indication was keratoconus [38.4%] followed by aphakic/pseudophakic bullous keratopathy [11.7%], previous failed grafts [10.6%], infectious corneal ulcers [10.1%], non-herpetic corneal scars [7.6%], trachoma keratopathy [4.7%], stromal corneal dystrophies [4.6%], post-herpetic corneal scar [3.7%], Fuchs' endothelial dystrophy [0.8%], and congenital hereditary endothelial dystrophy [0.4%]. Techniques of corneal transplantation included penetrating keratoplasty [PKP; 70.9%], deep anterior lamellar keratoplasty [DALK; 20.1%], conventional lamellar keratoplasty [LKP; 4.4%], and Descemet's stripping automated endothelial keratoplasty [DSAEK; 2.3%]. Over the study period, there was a significant increase in the relative frequency of infectious corneal ulcers, failed grafts, and trachoma keratopathy. Additionally, a significant reduction was observed in PKP and LKP procedures, and volume of DALK and DSAEK increased significantly. At final follow-up, 69.0% of grafts were clear in the PKP group. This figure was 82.6%, 82.7%, and 97.6% in the DALK, LKP, and DSAEK groups, respectively. Keratoconus was the most common indication and PKP was the most prevalent technique used for corneal transplantation. However, significant changes in the indications and surgical techniques were observed from 2004 to 2009

Dry eye syndrome

Our understanding of keratoconjunctivitis sicca [KCS], also known as dry eye syndrome, has been changed over recent years. Until lately, the condition was thought to be merely due to aqueous tear insufficiency. Today, it is understood that KCS is a multifactorial disorder due to inflammation of the ocular surface and lacrimal gland, neurotrophic deficiency and meibomian gland dysfunction. This change in paradigm has led to the development of new and more effective medications

Indications for corneal transplantation at a tertiary referral center in Tehran

To report the indications and techniques of corneal transplantation at a tertiary referral center in Tehran over a 3-year-period. Records of patients who had undergone any kind of corneal transplantation at Labbafinejad Medical Center, Tehran, Iran form March 2004 to March 2007 were reviewed to determine the indications and types of corneal transplantation. During this period, 776 eyes of 756 patients [including 504 male subjects] with mean age of 41.3 +/- 21.3 years underwent corneal transplantation. The most common indication was keratoconus [n=317, 40.8%], followed by bullous keratopathy [n=90, 11.6%], non-herpetic corneal scars [n=62, 8.0%], infectious by corneal ulcers [n=90, 11.6%], non-herpetic corneal scars [n=317, 40.8%] followed by bullous keratopathy [n= 61, 7.9%], previously failed grafts [n=61, 7.9%], endothelial and stromal corneal dystrophies [n=28, 3.6%], and trachoma keratopathy [n=26, 3.3%]. Other indications including Terrien's marginal degeneration, post-LASIK keratectasia, trauma, chemical burns, and peripheral ulcerative keratitis constituted the rest of cases. Techniques of corneal transplantation included penetrating keratoplasty [n=607, 78.2%], deep anterior lamellar keratoplasty [n=108, 13.9%], conventional lamellar keratoplasty [n=44, 5.7%], automated lamellar therapeutic keratoplasty [n= 8, 1.0%], and Descemet stripping endothelial keratoplasty [n=6, 0.8%] in descending order. The remaining cases were endothelial keratoplasty and sclerokeratoplasty. In this study, keratoconus was the most common indication for penetrating keratoplasty which was the most prevalent technique of corneal transplantation. However, deep anterior lamellar keratoplasty is emerging as a growing alternative for corneal pathologies not involving the endothelium

Higher-order aberrations in myopic eyes

To evaluate the correlation between refractive error and higher-order aberrations [HOAs] in patients with myopic astigmatism. HOAs were measured using the Zywave II aberrometer over a 6 mm pupil. Correlations between HOAs and myopia, astigmatism, and age were analyzed. One hundred and twenty-six eyes of 63 subjects with mean age of 26.4 +/- 5.9 years were studied. Mean spherical equivalent refractive error and refractive astigmatism were -4.94 +/- 1.63 D and 0.96 +/- 1.06 D, respectively. The most common higher-order aberration was primary horizontal trefoil with mean value of 0.069 +/- 0.152 micro m followed by spherical aberration [-0.064 +/- 0.130 micro m] and primary vertical coma [-0.038 +/- 0.148 micro m]. As the order of aberration increased from third to fifth, its contribution to total HOA decreased: 53.9% for third order, 31.9% for fourth order, and 14.2% for fifth order aberrations. Significant correlations were observed between spherical equivalent refractive error and primary horizontal coma [R=0.231, P=0.022], and root mean square [RMS] of spherical aberration [R=0.213, P=0.031]; between astigmatism and RMS of total HOA [R=0.251, P-0.032], RMS of fourth order aberration [R=0.35, P<0.001], and primary horizontal coma [R=0.314, P=0.004]. Spherical aberration [R=0.214, P=0.034] and secondary vertical coma [R=0.203, P=0.031] significantly increased with age. Primary horizontal trefoil, spherical aberration and primary vertical coma are the predominant higher-order aberrations in eyes with myopic astigmatism

Deep anterior lamellar keratoplasty: indications, surgical techniques and complications

The concept of lamellar keratoplasty [LK] is not new. However, it had been abandoned and largely replaced by the time-honored technique of penetrating keratoplasty [PK] because LK is technically demanding, time consuming and gives suboptimal visual outcomes due to interface irregularity arising from manual lamellar dissection. Recent improvements in surgical instruments and introduction of new techniques of maximum depth of corneal dissection as well as inherent advantages such as preservation of globe integrity and elimination of endothelial graft rejection have resulted in a re-introduction of LK as an acceptable alternative to con ventional PK. This review article describes the indications, different techniques, clinical outcomes and complications of deep anterior LK

Risk factors for posterior capsule rupture and vitreous loss during phacoemulsification

To determine the rate and risk factors of vitreous loss during phacoemulsi-fication in patients with cataracts operated by ophthalmology residents and fellows at Labbafinejad Medical Center. This prospective descriptive study included consecutive patients with cataracts undergoing phacoemulsification over a one year period. All patients were operated under local or general anesthesia using the divide and conquer technique. Preoperatively, all patients underwent a complete ocular examination including measurement of visual acuity, slitlamp biomicroscopy, intraocular pressure measurement, and dilated funduscopy. Main outcome measures included the rate of posterior capsular rupture and vitreous loss as well as associated risk factors such as surgical experience, ocular and systemic conditions, and type and severity of the cataract. Overall, 767 eyes of 767 patients with mean age of 63.7 +/- 10.3 [range, 25-91] years were operated. The overall rate of vitreous loss was 7.9% which was 5-fold greater in the hands of residents as compared to fellows. Among different factors, older age, female sex, small pupil, small capsulorrhexis, presence of pseudoexfoliation, and high myopia were significantly associated with vitreous loss. The highest rate of vitreous loss occurred in patients with dense nuclear cataracts. Considering the higher rate of vitreous loss in patients operated by ophthalmology residents; patients with known risk factors for vitreous loss should better be operated by more experienced surgeons

Acute hydrops following penetrating keratoplasty in a keratoconic patient

To report a case with history of penetrating keratoplasty [PK] for keratoconus that developed acute hydrops in the recipient and donor cornea. A 46-year-old man, with history of bilateral keratoconus, who had undergone corneal transplantation in his left eye, presented with complaints of sudden visual reduction, photophobia, redness and pain of the left eye. Review of his clinical course, slit-lamp biomicroscopy, laboratory evaluations including confocal microscopy and ultrasound biomicroscopy revealed acute hydrops in the graft. Second corneal transplantation was done for his left eye and pathologic examination confirmed the diagnosis. Acute hydrops can occur after PK in patients with keratoconus. Although this condition is not common, it should be considered as a differential diagnosis of graft rejection