JOURNAL OF CURRENT OPHTHALMOLOGY
Year:2009 | Volume:21 | Issue:2|Papers Count:12

In this issue of the Iranian Journal of Ophthalmology, Lashay and coauthors have presented a very meticulous and instructive article on "Surgical Outcomes of Complicated Retinal Detachments using Heavy Silicone Oil as an Internal Tamponade" (pages: 25-30). The authors have performed a complete pars plana vitrectomy, membrane peeling and injection of heavy silicone and endolaser in 55 eyes with complicated retinal detachment. They have obtained a significant improvement in the visual acuity of their patients (P=0.005) and claim that the functional results obtained in their study are consistent with previous reports of using heavy silicone oil in similar cases.

Introduction: In recent years, reduced corneal biomechanics have been identified as an important element in the pathogenesis of various corneal diseases. The biomechanical characteristics of a connective tissue such as strength and resistance against mechanical stress are indispensable prerequisites to maintain regular shape and function of that tissue. Intra- and intermolecular cross-links between collagen molecules are essential elements of these biomechanical properties. Accordingly, collagen cross-links occur physiologically in all organs and tissues with certain biomechanical characteristics.In other surgical fields, cross-linking has been used for decades to increase the biomechanical properties of connective tissue structures: in cardiac surgery, porcine aortic valve bioprosthesises are treated with glutaraldehyde prior to implantation to ensure increased cross-linking, which increases biomechanical resistance against biodegradation. Additionally, in otolaryngology, polymers inducing cross-linking are used in the treatment of destabilized vocal cords and for nasal reconstruction.In the cornea, a variety of conditions such as primary acquired (keratoconus and pellucid marginal corneal degeneration) and secondary induced (iatrogenic keratectasia after refractive laser surgery) ectatic disorders lead to a reduced biomechanical resistance. Corneal collagen cross-linking with riboflavin/UVA (CXL) represents a new approach to these diseases. To assist researchers and clinicians interested in the field, this article attempts to provide a structured overview on the current state of the method, basic principles, technique, and application of CXL in primary and iatrogenic keratectasia. Furthermore, it addresses safety issues and potential complications of the method.

Purpose: To study the pattern of perfusion of central retinal artery (CRA) after 0.1 ml intravitreal injection of bevacizumab to verify the need for any maneuver to decrease the intraocular pressure (IOP) including anterior chamber paracentesis (ACP).Methods: This is a prospective, interventional, noncomparative case series. Patients receiving intravitreal injection of bevacizumab for choroidal neovascularization (CNV) secondary to age-related macular degeneration, diabetic macular edema and retinal veno-occlusive diseases were included in the study. Each eye received 0.1 ml intravitreal injection of bevacizumab and the status of perfusion of CRA and its pulsation was monitored by indirect ophthalmoscopy until cessation of visible pulsation. Main outcome measures were patency of CRA, its pulsation and time from injection to cessation of pulsation.Results: Seventy seven eyes of 70 patients were studied. At first ophthalmoscopy 30 seconds after injection, CRA was open in all cases with or without pulsation. CRA occlusion was not observed in any case. In 20 eyes (26%) CRA was patent without pulsation. In 57 eyes (74%) CRA pulsation was detected and this visible pulsation of CRA stopped within an average time of 167±99 seconds (range: 30-480 seconds). From 17 eyes which had significant vitreous reflux, only 6 eyes had CRA pulsation which stopped in a mean time of 80±36 seconds. There was a significant difference between pulsation duration in patients with and without vitreous reflux (Mann-Whitney U test, P=0.005). Absence of postinjection vitreous reflux was a risk factor for CRA pulsation after intravitreal injection of 0.1 ml of bevacizumab (relative risk: 2.41, 95% CI: 1.25-4.62).Conclusion: Considering the absence of CRA closure and the short time needed for the cessation of pulsation after intravitreal injection of 0.1 ml bevacizumab, no treatment including ACP is warranted before or after such injections in nonglaucomatous eyes. Indirect ophthalmoscopy is a noninvasive useful maneuver to ascertain patency of CRA after intravitreal injections.

Purpose: To examine the relationship between retinal nerve fiber layer (RNFL) measurements obtained using scanning laser polarimetry with variable corneal compensation (VCC) and central corneal thickness (CCT) measurements using pentacam in myopic patients.Methods: The study included 45 eyes from 45 myopic patients with intraocular pressure (IOP) measurements£21 mmHg. All participants had normal optic discs and normal standard automated perimetry visual fields. All patients underwent imaging with the GDx VCC and pentacam. We examined the relationship between GDx VCC RNFL measurements and CCT.Results: Mean spherical equivalent (SE) was -3.65±1.1 D (range: -1.00 to -6.5 D). Mean CCT was 530.9±24.32 mm with a range of 488 to 596 mm. TSNIT (temporal, superior, nasal, inferior, temporal) average, inferior average, superior average, TSNIT standard deviation (SD) and nerve fiber indicator (NFI) were not correlated with CCT. There were no correlations between RNFL thickness and refraction, age, corneal volume and mean keratometry. However, RNFL in patients with CCT£530 mm was significantly thinner than in those with thick corneas.Conclusion: RNFL measurements obtained using GDx VCC may not correlate with corneal thickness (CCT) and refraction in myopic patients. Myopic patients with CCT£530 have thinner RNFL than in those with thick corneas.

Purpose: To evaluate the anatomical and functional outcomes of using heavy silicone oil as an internal tamponade for complicated cases of retinal detachment associated with proliferative vitreoretinopathy involving inferior retinal quadrants.Methods: 55 eyes from 55 patients with complicated retinal detachments enrolled in this interventional case series study. All eyes underwent standard three-port pars plana vitrectomy with endolaser photocoagulation and heavy silicon oil injection. Patients were categorized in traumatic and nontraumatic groups based on underlying retinal pathology. Anatomical and functional outcomes as well as complications were evaluated during 14 months (mean follow-up was 10.3 months), postoperatively.Results: 55 patients, 11 women, and 44 men with a mean age of 37.18±24.2 years (from 4 to 104 years) underwent pars plane vitrectomy with heavy silicone oil injection. Mean preoperative logMAR visual acuity was 2.24 (±0.78) which significantly improved to 1.55 (±0.63) (P<0.005). Retinal redetachment occurred in 11 (20%) at early postoperative period (first month postoperatively) that was successfully managed by reoperations. Heavy silicone oil was removed in 39 (70%) patients after a mean of 5.8 months. Retinal reattachment was ultimately achieved in 37 (67.3%) patients after a mean of 2.3 operations per patient. Reattachment rates were significantly lower in traumatic (48%) compared to nontraumatic (83.3%) group (P=0.038). Intractable glaucoma, retinal redetachment due to proliferative vitreoretinopathy and band keratopathy were among the observed complications.Conclusion: Heavy silicon oil internal tamponade is a safe and effective therapeutic modality in complicated retinal detachments associated with pathologies affecting inferior retinal quadrants.

Purpose: To evaluate the effect of radiation with Ruthenium-106 (Ru-106) plaques in the control of retinal vasoproliferative tumors.Methods: This study is a retrospective, interventional nonrandomized case series. Seven eyes of seven patients (four males and three females) with retinal vasoproliferative tumors were enrolled. The eyes were treated by Ru-106 plaques with mean apex dose of 39 Gy (range, 38-43 Gy) in low-dose (LD) group (four cases) and 79 Gy (range, 76-81 Gy) in high-dose (HD) group (three cases). Mean (±SD) follow-up duration was 18 (±8) months (range, six to 31 months) Main outcome measures were tumor thickness reduction and clinical and visual improvement.Results: Mean (±SD) preoperative logMAR visual acuity improved from 0.92 (±0.49) to 0.85 (±0.71) at the last follow-up (P=0.50). Significant exudative retinal detachments, which were presented before brachytherapy in five patients (71.4%), completely reabsorbed following brachytherapy. Radiation retinopathy was seen in three patients during the follow-up period. Tractional rhegmatogenous retinal detachment developed in one patient of LD group which was managed with pars plana vitrectomy and silicon oil tamponade.Conclusion: Brachytherapy with high-dose Ru-106 plaques is an effective treatment modality for retinal vasoproliferative tumors in terms of functional and anatomic results. Further investigations with enough sample sizes are suggested to identify the optimal apex dose.

Purpose: To evaluate the anatomical and functional outcomes of surgical management of retinal detachments associated with choroidal colobomas.Methods: In this retrospective study, 31 eyes of 31 patients with coloboma-related retinal detachments enrolled. All the eyes underwent standard three-port pars plana vitrectomy with internal tamponade with nonheavy silicon oil in 24 (77.4%) or 20% sulfur hexafluoride (SF6) in 7 (22.6%) eyes. Endolaser photocoagulation at the borders of the coloboma was performed in all cases to isolate the colobomatous area. Encircling band was placed in 12 (38.7%) eyes based on surgeon’s intraoperative judgment. Intraoperative lensectomy was performed in 16 (51.6%) eyes.Results: Mean (±SD) preoperative visual acuity (VA) was 2.41 (±0.73), which showed a statistically significant improvement to 1.78 (±0.93), postoperatively (P<0.001). Placement of encircling band significantly increased the chance of postoperative intraocular pressure (IOP) elevation (P=0.027). Retinal reattachment was ultimately achieved in 29 patients (93.5%) after an average of 1.32 operations per patient. Intractable glaucoma, retinal redetachment, band keratopathy, corneal decompensation and macular whole formation were the complications observed.Conclusion: Using vitrectomy techniques with intraoperative silicon oil or SF6 tamponade and endolaser photocoagulation at the borders of the coloboma is highly successful in anatomical retinal reattachment accompanied by significant visual improvement.

Purpose: To investigate the results of deep lamellar keratoplasty (DLK) by big bubble method with using shifting bubble sign in patients suffering from keratoconus or corneal opacity.Methods: In this prospective interventional clinical trial, 20 eyes of 18 patients (10 males and 8 females) who underwent DLK by big bubble method using shifting bubble sign were investigated. Mean age of cases were 26.94 years old (19 to 66 years). Keratoplasty was done as a treatment of keratoconus in 18 cases (90%) and corneal opacity due to trachoma in 2 cases (10%).Results: In this study, 20 eyes of 18 patients who underwent DLK by big bubble method using shifting bubble sign were investigated. Best corrected visual acuity (BCVA) of 14 cases (70%) were equal or lower than 20/200 and in 6 cases (30%) were between 20/200 and 20/50. Mean uncorrected visual acuity of all cases in the first, third, sixth and twelfth months of follow-ups were 20/160, 20/120, 20/120 and 20/80 respectively. Mean of BCVA of cases after one year was 20/35 (20/20 to 20/120). Micro perforation occurred in 3 cases (15%) during the procedure, but DLK were not converted to penetrating keratoplasty (PK) in any of the cases. Vascularization and corneal opacity was occurred in 2 cases (10%) at the junction of donor and recipient cornea.Conclusion: DLK by big bubble method is an effective way to treat the keratoconus or corneal opacity and using shifting bubble sign will confirm formation of the big bubble. The results of this study are comparable with similar previous studies on the same subject.

Purpose: To image leukocyte adherence to the vascular endothelium and extravasation into surrounding tissues in neovascularized corneas using acridine orange, a selective DNA stain, in rats.Methods: Corneal neovascularization was induced by placing two sutures in the cornea of one eye of 12 Long-Evans rats. One week later, acridine orange (4 mg/kg) was injected via the tail vein and the eyes were evaluated using a scanning laser ophthalmoscope (SLO) 3-5 minutes, 20 minutes, and one hour after injection. Images were recorded on videotape for further analysis.Results: Acridine orange staining showed adherent leukocytes in corneal vessels at 3-5 minutes post-injection. After 20 minutes, leukocytes were seen in the corneal vessels and in the surrounding tissues. At 1 hour post-injection, decreased number of leukocytes was visible in the tissues, but none were seen in the corneal vessels.Conclusion: Acridine orange effectively demonstrate the leukocyte / endothelial interactions (leukocyte adherence) in the blood vessel, as well as leukocyte infiltration of surrounding tissues in neovascularized corneas. This technique may have prognostic value in corneal disease in which neovascularization is the pathologic component.

Purpose: To compare thickness of central cornea measured using Pentacam, Orbscan II, and ultrasound pachymeter.Methods: Patients with no history of corneal diseases or systemic diseases affecting eyes, who did not wear contact lens or use eye medications, and who with no previous history of corneal surgery were selected for this study. Central corneal thickness (CCT) was measured by three methods using Pentacam, Orbscan II, and ultrasound pachymeter.Results: Comparison of ultrasound and Orbscan CCT measurements showed a relatively high correlation between these two devices (P<0.001; r=0.891). The 95% limits of agreement (LoA) between these two devices were -42.44 to 20.18 mm. There was also a high correlation between the results obtained through ultrasound and Pentacam (P<0.001; r=0.932). The 95% LoA of CCT with ultrasound and Pentacam were -13.35 to 24.16 mm. There was also a high correlation between CCT measurements carried out by Orbscan and Pentacam (P<0.001) and the 95% LoA were -12.14 to 45.19 mm.Conclusion: The findings of the present study demonstrated high agreements between the CCT readings measured with Orbscan, Pentacam, and ultrasound. The agreement between the Pentacam and ultrasound measurements was higher than that of between Orbscan and ultrasound, making Pentacam a better substitute for ultrasound.

Purpose: To report occurrence, management, and outcome of late-onset traumatic dislocation of laser in situ keratomileusis (LASIK) flaps.Case report: We report a patient with late-onset LASIK corneal flap dislocation after blunt ocular trauma occurring four years after surgery. An ultrasound biomicroscopy (UBM) was performed to view the status of flap and determination of flap thickness.Results: Repositioning of the flap was performed in the operation room. During repositioning, the surface of the bed was debrided and deepithelialized, then the dislocated flap was floated into position with the aid of an iris spatula. A bandage contact lens was placed and topical antibiotic and corticosteroids were given postoperatively. The dislocated corneal flaps were successfully repositioned. After 3 months, the uncorrected visual acuity (UCVA) was 20/30 and the best corrected visual acuity (BCVA) was 20/25 with a refraction of +0.25-0.5×10.Conclusion: LASIK corneal flaps are vulnerable to traumatic dehiscence and dislocation. UBM is a useful and easy to perform technique and show the anatomical status of the flaps.

Purpose: Congenital third nerve palsy was generally thought to exist in isolation without associated abnormalities. In this report, we present a case of congenital third nerve palsy in osteogenesis imperfecta.Methods: A 6-month-old girl with osteogenesis imperfecta presented with ptosis and large incomitant exotropia in left eye (LE) at birth. Ocular examination revealed total third nerve palsy in LE. Brain CT scan was normal. She underwent surgery for strabismus at the age of two years and surgery for ptosis after four months.Results: Ocular alignment has greatly improved after recess-resect procedure on the horizontal rectus muscles in LE. She achieved a good functional outcome after ptosis surgery.Conclusion: Congenital third nerve palsy may associate with systemic disease. To our knowledge, this represents the first report on demonstrating this association in osteogenesis imperfecta.