Silicone Oil Instillation Research Articles

Change in refraction, corneal power and axial length of the eye secondary to silicone oil tamponade injection after pars plana vitrectomy

Background: Refractive and ocular biometric changes after silicone oil tamponade (SOT) in phakic eyes have been studied thoroughly; however, similar studies amongst Sudanese patients with vitreoretinal conditions were not carried out.Aim: This study aimed to assess post-operative changes in refraction, corneal power and axial length after pars plana vitrectomy (PPV) with SOT in phakic patients.Setting: The study was conducted at Sudan Eye Center, Khartoum, Sudan.Methods: A cross-sectional retrospective hospital-based study was performed at Sudan Eye Center. The study included all phakic patients who underwent PPV with SOT for a variety of vitreoretinal conditions from October 2018 to January 2019. Clinical investigations included uncorrected visual acuity (VA), best-corrected VA, refraction, corneal power and axial length pre- and post-surgery. Differences in these parameters were assessed using a paired sample t-test with a significance level of 0.05.Results: Medical records of 59 consecutive patients (59 eyes, 41 men and 18 women) with ages ranging from 22 years to 75 years were studied. The findings revealed a statistically significant hypermetropic change (pre: –0.17 ± 2.44 dioptre [D] and post: +4.43 ± 2.04 D) with a p-value of 0.001. In terms of axial length, there was a significant increase (pre: 23.61 ± 1.17 mm and post: 23.82 ± 1.27 mm; p 0.001). However, no significant change was found in corneal power (pre: –43.60 ± 1.96 D and post: 43.63 ± 2.03 D; p = 0.45).Conclusion: A hypermetropic shift in refraction, longer axial length and non-considerable increase in corneal power were observed amongst Sudanese phakic patients after PPV with instillation of silicone oil.

The Influence of the Type of Anaesthesia on the Frequency of Postoperative Haemorrhage Requiring Revision After Removal of the Silicone Oil Tamponade

In this retrospective data analysis, it was examined whether the mode of anesthesia influenced postoperative haemorrhage in patients with first time complete silicone oil removal in 2002, 2005, 2010, 2014 - 2016 in our clinic and if there was a change in frequency over time. Haemorrhage was defined as a postoperative haemorrhage within 2 weeks after the operation and which led to revision vitrectomy. In all, there were 939 operations and 9 cases of postoperative surgery requiring revision in the analysed years. Even though the number of patients with intubation anesthesia (355) was smaller than the number with local anesthesia (584), the majority of patients with postoperative haemorrhage had been given intubation anesthesia (6). This difference corresponds to a trend (p = 0.089) towards a lower rate of postoperative haemorrhage with local anesthesia, which could encourage the surgeon to perform silicone oil removal under local anaesthesia. Over the course of time, there was a decline in postoperative haemorrhage. In 2002, 2005 and 2010 there were 7 cases of postoperative haemorrhage, but only 2 in the years 2014 - 2016. Aside from the higher proportion of operations under local anaesthesia, the decline in the frequency of postoperative haemorrhage may be attributed to "smoother extubation", the emergence of trocar-guided surgical procedure and the use of anti-VEGF therapy - all leading to a change in the spectrum of illnesses treated by silicone oil instillation.

The clinical study of intravitreal Ranibizumab injection before vitrectomy for proliferative diabetic retinopathy

Objective To investigate the therapeutic effect of 25 G+ vitrectomy assisted with preoperative intravitreal injection of Ranibizumab for the treatment of proliferative diabetic retinopathy. Methods A prospective controled analysis in 74 eyes of 73 cases with proliferative diabetic retinopathy treated by vitrectomy from May 2013 to January 2015 was performed. Thirty-four eyes of 33 cases with proliferative diabetic retinopathy received intravitreal injection of Ranibizumab 0.05ml(contain ranibizumab 0.5mg)at 5 to 7 days before the vitrectomy in group A. Forty eyes of 40 cases with proliferative diabetic retinopathy were treated by vitrectomy only as non-injection group (group B). The operative time, hemorrhage during the operation, times of endodiathermy, incidence of iatrogenic retinal tear, kinds of intraocular filling materials, postoperative visual acuity and complications between the two groups were compared. Results The average operation time in group A was (92.0±19.5)min less than (121±26.3)min in group B , the difference was statistically significant (t=6.837, P=0.041) .Hemorrhage during the operation were observed in 9 eyes in group A (26.5%), and 24 eyes(60.0%) in group B(χ2=8.362, P=0.005) .Endodiathermy was used 16 times in group A, and 47 times in group B(t=2.216, P=0.032). The iatrogenic retinal tear occurred in 4 eyes(11.8%) in group A, and 7eyes(17.5%)in group B(χ2=0.478, P=0.533). The kinds of intraocular filling materials were silicone oil instillation in 14 eyes (41.2%), expanding gas instillation in 4 eyes(11.8%), balanced salt solution in 16 eyes(47.1%)in group A, and silicone oil instillation in 27 eyes (67.5%), expanding gas instillation in 4 eyes(10.0%), and balanced salt solution in 9 eyes(22.2%)in group B(χ2=5.632, P=0.060). The vision of group A was better than that of group B(χ2=8.527, P=0.014). There was no difference at 3d and 2weeks after sugery between the vision of two groups. There was no one complicated with vitreous hemorrhage postoperatively in group B, but 4 eyes had that in group A, the difference was not significant (Fisher P=0.120). Conclusion Vitrectomy assisted with preoperative intravitreal injection of Ranibizumab can decrease the operation time, reduce the incidence of hemorrhage during the operation, and obtain better visual acuity in the treatment of proliferative diabetic retinopathy. Key words: Diabetic retinopathy, proliferative; Vitrectomy, 25 G+; Ranibizumab, intrevitreal injection, before surgery

Calcification of Hydrophilic Acrylic Intraocular Lenses With a Hydrophobic Surface: Laboratory Analysis of 6 Cases

To investigate the nature and characteristic features of deposits causing opacification of intraocular lenses (IOLs) based on the examination of clinical findings using scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) analysis. Retrospective, observational case series. This is a multicenter study of 6 hydrophilic acrylic IOLs (Lentis LS-502-1; Oculentis GmbH, Berlin, Germany) with a hydrophobic surface that were explanted from 5 patients because of opacification. Three patients had an uncomplicated phacoemulsification. One patient underwent combined phacoemulsification and pars plana vitrectomy for retinal detachment and later silicone oil endotamponade owing to redetachment. The last patient had a pars plana vitrectomy and silicone oil instillation combined with phacoemulsification for tractive retinal detachment and diabetic retinopathy. The explanted lenses were submitted to our laboratory and were examined by SEM and EDX in order to identify the morphologic features and the composition of the deposits. SEM and EDX analyses confirmed the presence of calcific deposits in the interior of the opacified hydrophilic IOLs, with a pattern showing the formation of lumps on the surface. The lumps were due to subsurface formation of calcium phosphate crystalline deposits. The crystallite clusters seemed to diffuse from the IOL interior to the surface. We demonstrated the calcification pattern of the hydrophilic IOL (Lentis LS-502-1) with a hydrophobic surface. Although hydrophilic acrylic lenses have a hydrophobic surface, the development of calcification is a possible threat initiating from the hydrophilic subsurface of the IOLs.

Postoperative hyperopic shift after cataract surgery in silicone oil‐filled eyes

Vitrectomy with silicone oil (SO) instillation has been widely used in complicated vitreoretinal diseases to achieve retina stability. Because progressive lens opacity is common after vitrectomy and SO infusion, the removal of SO and cataract extraction with intra-ocular lens (IOL) implantation may be performed in the same setting. The refractive outcomes of cataract surgery with simultaneous SO removal have shown acceptable results. However, the refractive outcome after cataract surgery is less predictable in some complicated cases in which intravitreal SO is retained to achieve a long-term tamponade effect. We investigate the refractive outcome of cataract surgery in 21 SO-filled eyes with complicated vitreoretinal diseases and compare the results with those in 42 vitrectomized eyes without SO instillation. The SO used in our study was 5000 centistokes. Axial length (AL) measurements were performed using contact A-scan echography (Sonomed A-2500, New York, NY, USA). To adjust the falsely elongated AL due to the low sound velocity in SO, the following formula was used: AL = anterior chamber depth + lens thickness + vitreous length *0.68. IOL power was calculated using the SRK-T formula. In all SO-filled eyes, we generally chose a more myopic calculated target refraction when deciding the IOL power to compensate for the possible hyperopic shift due to a higher refractive index of SO (Stefansson et al. 1988; Smith et al. 1990; Hotta & Sugitani 2005). Foldable acrylic IOLs (AcrySof SA60AT for power ≧6 D or AcrySof MA60MA for power<6 D; Alcon Surgery) were implanted into the capsular bag in all eyes. Intergroup comparison was shown in Table 1. The refractive outcomes in the SO-filled group were more variable (1.07 ± 2.26 D versus −0.57 ± 1.15 D) and showed a significant tendency of hyperopic shift (+2.89 ± 2.15 D versus + 0.04 ± 1.0 D, p < 0.001). Eyes in the SO-filled group had a higher proportion of cases undergoing scleral buckling procedure, a shorter anterior chamber depth (ACD) and a longer adjusted AL in average. In one eye in the SO-filled group, the refraction changed from +3.25 D after cataract surgery to 0 D after SO removal 3 years later. The uncertainty of postoperative refraction after cataract surgery in SO-filled eyes is due to several perioperative factors. In our study, the SO-filled group had significantly longer average AL and shorter average ACD, which might be related to a higher rate of scleral buckling procedure performed in those eyes. A longer AL could augment the SO-induced acoustic signal attenuating effect and make the measurement less reliable (Ghoraba et al. 2002). Previous studies found that a hyperopic shift in refraction would be induced when vitreous was replaced with SO through vitrectomy in phakic or pseudophakic eyes (Stefansson et al. 1988; Smith et al. 1990; Hotta & Sugitani 2005). This tendency of SO-induced hyperopic shift was also noted in our study. However, the amount of hyperopic shift showed great variation among different studies. The posterior convex curvature of the IOL is thought to be related to the amount of hyperopic shift (Hotta & Sugitani 2005). Incomplete SO filling in the vitreous cavity causing changes in curvature and contact area of SO-fluid interface in different head positions may also result in variability in refractions and AL measurement (Dick et al. 1997). In conclusion, the refractive results of cataract surgery in SO-filled eyes were generally more variable than in simply vitrectomized eyes. Because a mean hyperopic shift is about 3.0 D in our study, we suggest choosing −2.5 to − 3.0 D target refraction, which may partially compensate for the SO-induced hyperopic shift, if SO is intended to be left for a long-term tamponade effect.

Colored perfluorocarbon liquids as novel intraoperative tools

Perfluorocarbon liquids (PFCLs) are used as intraoperative tools to stabilize the retina during vitreoretinal surgeries. Their use would be much facilitated if PFCLs were colored and not transparent. We describe the development of a colored PFCL for vitreoretinal surgeries. Perfluorohexyloctan (F6H8) was colored by adding a blue, biocompatible anthraquinone dye, and then mixed with perfluorodecalin (PFD) or perfluorooctane (PFO) at different volume percentages. The thus-obtained colored PFCLs were incubated with lens, lens capsule, vitreous body, and retina of enucleated porcine eyes for staining purpose and analyzed microscopically. To analyze possible interactions between colored PFCLs and silicone oil, colored PFCLs were exchanged to BSS and silicone oil respectively in enucleated pig eyes. By mixing different volume% of colored F6H8 with perfluorodecalin (PFD) or perfluorooctane (PFO), colored PFCLs of different density and staining intensity were obtained. Cornea, lens, lens capsule, vitreous, and retina showed no signs of staining after incubation with colored PFCLs for 10min. Colored PFCLs were transparent despite intense coloring, thus allowing a clear visibility of the underlying tissue. Immediately after instillation of silicone oil, the colored PFCL bubble was well-defined, and colored PFCL was easily aspirated. After 5 minutes reaction time, considerable diffusion of the dye from the PFCL bubble into the silicone oil was observed. The staining intensity can be varied according to the volume% of the colored F6H8 phase. Colored PFCL is clearly visible when installed in the vitreous cavity of a pig eye, and can easily be removed. It does not stain the intraocular tissues in pig eyes. Colored PFCL can be exchanged with silicone oil. But a time-dependent diffusion of the dye into the silicone oil was observed in pig eyes, indicating that the contact should be limited.

Changes in visual acuity, axial length, and refraction after removal of intraocular silicone oil following retinal reattachment surgery in Chinese patients: An open-label, prospective study

Background: As a vitreous substitute for long-term tamponade, silicone oil is widely used in vitreoretinal surgery to treat retinal detachment with proliferative vitreoretinopathy and some internal reconstruction after globe trauma. Objectives: The aim of this study was to compare the changes in visual acuity, axial length, and refraction in eyes before and after removal of intraocular silicone oil of 2 different viscosities after retinal reattachment surgery. The difference in the final anatomic success (stable retinal reattachment) rate was also assessed. Methods: Patients with surgically reattached retinas were enrolled in this open-label, prospective, nonrandomized study. All patients underwent pars plana vitrecto-my, lensectomy, scleral buckling or encircling, and epiretinal membrane dissection; silicone oil was removed after stable retinal reattachment was achieved. Refraction, axial length, final visual acuity, and stable retinal reattachment were assessed ≤2 days prior to surgery (baseline) and ≤1 month after silicone oil removal. Refraction was measured using an autorefractometer, and axial length was measured using A-scan ultrasonography, while visual acuity was assessed using a standard Snellen chart. Results: Of the 96 eyes assessed for inclusion, 89 eyes of 89 Chinese patients (mean [SD] age, 36.8 [4.3] years) were included in the study. Forty-two eyes (47.2%) were filled with 3700-centistoke (cS) silicone oil and 47 (52.8%) were filled with 5000-cS silicone oil. The mean interval between instillation and removal of the silicone oil was similar between the 3700-cS and 5000-cS groups (5.37 vs 5.10 months, respectively). The mean changes in visual acuity from before surgery to after removal of the silicone oil in the 3700-cS and 5000-cS groups were not significantly different (13/100 vs 15/100). The mean increase in axial length was also not significantly different in the 3700-cS group compared with the 5000-cS group (11.92 [1.97] vs 12.33 [1.28] mm). Mean decrease in refraction was significantly lower in the 3700-cS group compared with the 5000-cS group (5.80 [1.51] vs 6.88 [2.31] diopters; t = 2.57, P < 0.05). The anatomic success rate was 92.9% (39/42 patients) in the 3700-cS group and 91.5% (43/47) in the 5000-cS group. Conclusions: A statistically significant decrease in refraction from baseline was found in the 3700-cS group compared with the 5000-cS group in these Chinese patients who underwent instillation and removal of silicone oil after retinal reattachment surgery. There were no other statistically significant differences between the 2 groups.

Ergebnisse der Aphakiekorrektur durch retroiridal fixierte Kunstlinse

We report the results of the secondary implantation of retroiridally fixated irisclaw-lenses (Artisan(R)) to correct aphakia. This retrospective study included all eyes that had undergone outpatient implantation of an Artisan IOL by the senior author (MK) between July 2004 and January 2008. We analysed 48 eyes of 46 patients (27 female, 19 male) aged 17 to 87 years. Underlying conditions were: aphakia after congenital cataract or trauma (19 eyes), late luxation of a posterior chamber IOL (16 eyes), intraoperative zonulolysis during cataract surgery that did not allow PC IOL implantation (12 eyes, including 10 eyes with pseudoexfoliation and one eye with Marfan syndrome), anterior chamber IOL with corneal decompensation problems and recurrent hyphema (1 eye). Simultaneous surgical procedures included: anterior vitrectomy (48 eyes), pars plana vitrectomy (14 eyes), removal of PC IOL (16 eyes), removal of AC IOL (1 eye), and penetrating keratoplasty (1 eye). Mean follow-up was 14.3 months (range: 1 - 31 months). IOL power was calculated using the SRKT formula and an A constant of 116.7. Surgery was uneventful in all cases with safe enclavation of both IOL haptics. Mean postoperative refraction was 0 dpt. (range: -0.75 to + 1.0 dpt.), median postoperative visual acuity in Log-Mar was 0.2; compared to preoperative visual acuity (median 0.4 Log-Mar); all patients improved. Pre- and postoperative intraocular pressures were in the normal range in all eyes. Complications were few: one eye without patent iridotomy developed pupillary block glaucoma one day following surgery and was successfully treated by Nd:YAG iridotomy. One patient following blunt ocular trauma developed a retinal detachment with PVR 10 months following implantation of the Artisan IOL that was repaired uneventfully by pars plana vitrectomy with silicone oil instillation. In this case, the Artisan IOL was left in place. In two eyes, secondary trauma resulted in dislocation of one haptic of the Artisan IOL. In both of these cases, refixation of the Artisan IOL was easily performed by enclavation of the iris claw. In two patients cystoid macula oedema was observed. With correct indications the implantation of a retroiridally fixated IOL (Artisan) is a safe and predictable method to correct aphakia and has become our method of choice instead of anterior chamber IOLs and sclera fixated IOLs.

Management der Bulbusruptur

Globe rupture is one of the most severe open globe injuries, permanently impairing visual acuity or leading to blindness. The risk of globe rupture is increased after previous intraocular surgery (27-fold), in myopia, older age, females, and after sudden falls. The differentiation between an occult globe rupture and severe ocular contusion may be complicated by pronounced subconjunctival hemorrhage with conjunctival swelling. In case of doubt, a rupture of the eyeball should be ruled out after a severe blunt ocular trauma. Limbal and scleral exploration after 360 degrees peritomy leads to the correct diagnosis. Immediate and watertight wound closure is essential to avoid expulsive choroidal hemorrhage, persisting ocular hypotony or epithelial ingrowth. Delayed wound closure raises the risk of posttraumatic endophthalmitis. Early vitrectomy may prevent tractional retinal detachment in case of retinal injury with vitreal bleeding. Silicone oil instillation stabilizes the central retina after open globe injury; scleral buckling is controversial.

Is silicone oil optic neuropathy caused by high intraocular pressure alone? A semi-biological model

Background:Silicone oil endotamponade is used for the repair of complicated retinal detachments. Cataract, glaucoma and corneal endothelial dysfunction are the most frequent complications of silicone oil tamponade. Clinical and histopathological...

Early Postoperative Macular Features Determined by Optical Coherence Tomography After Idiopathic Macular Hole Surgery With Silicone Oil Tamponade

The configuration of idiopathic macular holes in the early postoperative period after pars plana vitrectomy using optical coherence tomography through silicone oil was evaluated. Pars plana vitrectomy with internal limiting membrane peeling and silicone oil instillation was performed on 20 eyes. Optical coherence tomography images were obtained preoperatively and postoperatively. Nineteen eyes (95%) achieved a closed fovea. None of them had a transit foveal contour with flat retina without closure. In the early phase of postoperative idiopathic macular hole repair, inner retinal tissue closure rather than flattening of the fovea is essential for those undergoing pars plana vitrectomy with internal limiting membrane peeling and silicone oil instillation.

REFRACTIVE CHANGES IN SILICONE OIL–FILLED PSEUDOPHAKIC EYES

We examined the refractive changes in pseudophakic eyes of patients with idiopathic macular hole treated with silicone oil injection. Twenty consecutive eyes of 19 patients with idiopathic macular hole who had undergone successful pars plana vitrectomy using silicone oil tamponade were studied retrospectively. Lensectomy with intraocular lens (IOL) implantation was performed on each patient before vitreous surgery. Five biconvex type IOL models were used. After pars plana vitrectomy and fluid-air exchange, silicone oil was injected to replace the air completely. Macular hole closure was confirmed by optical coherence tomography, and silicone oil removal was performed. Manifest refractions before silicone oil filling, with silicone oil filling, and after silicone oil removal were determined. A mean hyperopic shift +/- SD in spherical equivalents of +5.69 +/- 1.71 diopters (P < 0.0001) was observed with silicone oil instillation. In contrast, a mean myopic shift +/- SD of -5.63 +/- 1.33 diopters was observed after silicone oil removal (P < 0.0001). The absolute value of the refractive shift showed a strong correlation with the posterior radius of the IOL (r = 0.699, P < 0.0001). IOL models with steeper posterior convex curvature result in larger refractive deviations in patients scheduled for silicone oil instillation.

Posterior fibrous pseudometaplasia of lens epithelial cells in phacic eyes filled with silicone oil.

Today, intravitreal silicone oil injection is a standard procedure for complicated cases of retinal detachment. Although cataract formation is found frequently following this procedure only few studies deal with histological lens changes. We report histological findings including ultrastructural studies of a special variety of posterior subcapsular cataract formation in six human eyes filled with silicone oil. In the posterior subcapsular area of the lens we found spindle-shaped cells resembling fibroblasts which were, however, entirely surrounded by basement membrane (a feature of epithelial cells) and were associated with collagen fibrils (a feature of fibroblasts). We termed this phenomenon posterior fibrous pseudometaplasia of lens epithelium, since we presumed a posterior migration of lens epithelial cells followed by production of collagen by these cells, without actual transformation to fibroblasts, however. Silicone oil instillation may result in the development of posterior fibrous pseudometaplasia, which is the final common pathway of alteration of lens epithelium and which was interpreted as a partial change, or change of certain characteristics of posteriorly migrated lens epithelial cells due to metabolic alterations.

Phacoemulsification combined with silicone oil removal through a posterior capsulorhexis

Purpose: To evaluate the technique of silicone oil removal through a posterior capsulorhexis combined with phacoemulsification and intraocular lens (IOL) implantation. Setting: Dr. Rajendra Prasad Center for Ophthalmic Sciences, New Delhi, India. Methods: Fifteen eyes of 15 patients had phacoemulsification with removal of silicone oil, which had been used for intraocular tamponade after a previous pars plana vitrectomy. Eyes with a stable retina were included in the series. In all eyes, the silicone oil was removed through a planned posterior capsulorhexis after phacoemulsification. The parameters evaluated were the primary diagnosis, duration between silicone oil instillation and phacoemulsification, type of cataract, preoperative and postoperative best corrected visual acuities (BCVAs), and complications such as frequency of retinal redetachment and secondary cataract. Results: Vitreoretinal surgery with silicone oil instillation was performed for rhegmatogenous-tractional detachment resulting from Eales’ disease in 6 eyes and from proliferative diabetic retinopathy in 2 eyes, for primary rhegmatogenous retinal detachment in 6 eyes, and for traumatic rhegmatogenous detachment in 1 eye. The mean duration between the silicone oil instillation and phacoemulsification was 7.5 months ± 3.8 (SD). Fourteen eyes had posterior subcapsular cataract, and 10 had nuclear sclerosis. Preoperative BCVA was worse than 6/60 in all eyes. The BCVA was 6/60 or better in 9 eyes after a minimum follow-up of 6 months. Two eyes had choroidal detachment in the early postoperative period. No eye had vitreous hemorrhage, retinal redetachment, secondary cataract, clinically significant endothelial decompensation or macular edema, or a dislocated IOL. Conclusion: The results indicate that silicone oil removal through a posterior capsulorhexis during phacoemulsification is a viable option and can be performed in selected cases of cataract with previous silicone oil instillation and a stable retina.

Macular hole surgery in an eye with an optic pit

PURPOSE: To report an eye with a full-thickness macular hole and an associated optic pit and the noteworthy intraoperative findings. METHODS: Case report. A 56-year-old woman presented with visual acuity LE: 20/100, a full thickness macular hole, and an optic pit. Optical coherence tomography and ophthalmic examination were performed preoperatively and postoperatively. RESULTS: Although usually a macular hole associated with an optic pit tends to be a lamellar and characterized by outer layer defects within preexisting macular detachments or schisis-like cavities, this type of macular hole was not presented in this case. Although the macular hole resembled the idiopathic type on clinical examination as well as on optical coherence tomography, it could only be closed in the third surgical attempt after using silicone oil as a long-standing tamponade. Peeling of an epiretinal membrane or the internal limiting membrane was not possible during any of the three surgeries. CONCLUSION: Our observations suggest that in cases of macular hole in association with optic pit, instillation of silicone oil should be considered in the first surgical procedure, especially if no epiretinal membrane or internal limiting membrane peeling is possible intraoperatively.

Intraocular pressure and silicone oil endotamponade.

To evaluate intraocular pressure after instillation and eventual removal of silicone oil in patients undergoing pars plana vitrectomy combined with silicone oil endotamponade. The study included 198 patients who underwent pars plana vitrectomy with silicone oil endotamponade (5,000 centistoke viscosity), in whom silicone oil was removed and in whom follow-up after oil removal was at least 3 months. All patients were operated on by one of two surgeons. After silicone oil instillation, intraocular pressure increased significantly (P < 0.001) from 12.9 +/- 4.4 mm Hg preoperatively to 16.1 +/- 5.5 mm Hg postoperatively. Intraocular pressure was statistically (P > 0.20) independent of the duration of silicone oil tamponade. Twenty percent of the 198 patients had at least one postoperative intraocular pressure measurement that was higher than 21 mm Hg. Main reasons for increased intraocular pressure were closed inferior iridectomy, iris neovascularisation, silicomacrophagocytic open-angle glaucoma secondary to silicone oil emulsification, and preoperative history of glaucoma. Glaucomatous optic nerve damage was detected in 14 (14 of 198, 7.1%) eyes, including 8 eyes with preoperative antiglaucoma treatment. Silicone oil emulsification occurring in 40 (40 of 198, 20.2%) patients did not statistically influence intraocular pressure after oil removal. Ocular hypotony occurred in 10 (10 of 198, 5.1%) patients after oil release leading to intraocular hemorrhages and loss of vision in 3 patients. Clinically significant increased intraocular pressure after pars plana vitrectomy with silicone oil endotamponade occurs relatively rarely, can usually be well controlled by topical antiglaucoma medication, and is reversible in most patients after oil removal. In patients with increased intraocular pressure and silicone oil endotamponade, oil removal may be preferred to invasive antiglaucoma surgery to reduce intraocular pressure.

Posterior pars plana high frequency capsulotomy

In special forms of complicated secondary cataract, especially after a cataract operation in eyes with proliferative disease and after a cataract operation associated with pars plana vitrectomy and silicone oil instillation, surgical capsulotomy must be performed. We developed a new surgical technique for posterior capsulorhexis via pars plana by using the high-frequency capsulotomy method developed by Klöti. We analyzed 14 consecutive patients undergoing late pars plana capsulotomy using a specially designed instrument for radiofrequency capsulorhexis. The indication for surgical capsulotomy was extreme secondary cataract; in 6 eyes fibrosis was associated with vascularizations. The high-frequency technique for posterior capsulotomy allowed reliable and precise tissue cutting. The cutting required minimal application of pressure to the capsule, and therefore damage to zonula fibers is minimized. Furthermore, use of the radiofrequency technique permitted hemostatic incision in vascularized membranes by inducing a fine coagulation margin. Posterior capsulorhexis using radiofrequency offers precise and effective tissue cutting if surgical capsulotomy is necessary.

Prophylactic argon laser coagulation for rhegmatogenous retinal detachment in AIDS patients with cytomegalovirus retinitis.

The incidence of cytomegalovirus (CMV) retinitis in patients with acquired immunodeficiency syndrome (AIDS) reaches 20-45%. Despite aggressive medical treatment, rhegmatogenous retinal detachments develop in up to 30% of the affected eyes. Surgical repair is often difficult due to multiple large and hardly visible retinal holes with vitreal traction. Pars plana vitrectomy with instillation of silicone oil is the procedure of choice, giving limited functional results with anatomical reattachment. We performed prophylactic laser coagulation in AIDS patients with medically treated CMV retinitis to prevent a progressive retinal detachment. Twenty-two quiescent CMV lesions in 22 eyes of 20 patients were treated with argon green laser coagulation. Each CMV lesion was completely surrounded with a double or triple row of laser spots (500-600 mumols; 0.2 s; gray-white lesions). The duration of follow-up was 2-24 months. Histopathologic evaluation was possible in two eyes of one patient. Reactivated or smoldering CMV retinitis crossed the laser scars in 11 eyes, making additional laser coagulation necessary. In four eyes retinal holes in the CMV scar tissue led to retinal detachment, which stopped at the laser scar. In three eyes the detachment is still controlled by the laser scar. In one eye, the detachment stopped at the laser scar for 6.5 months and then slowly progressed across it. There were no complications associated with our laser treatment. Prophylactic argon laser coagulation in quiescent CMV retinitis seems to reduce the rate of progressive retinal detachment with no need for vitrectomy and silicone oil tamponade.

Effect of head position on refraction in aphakic and phakic silicone-filled eyes.

The refraction of the eye is altered significantly after the instillation of silicone oil into the vitreous cavity because of the silicone oil's high refractive index. The degree of the refractive change shows diurnal variation and depends on the patient's head position. To analyze the degree and time course of refractive changes with respect to head position, the authors performed objective refraction in five aphakic and five phakic silicone oil-instilled eyes with attached maculae using an automatic hand-held refractometer. In each patient, 25 measurements were taken at short intervals using a hand-held autorefractometer with the patient in different positions (supine, head tilted down, and primary eye position). The highest shift of refraction was +5.95 +/- 2.63 diopters spherical equivalent in aphakic eyes and +2.45 +/- 0.71 diopters in the phakic eyes after the patient's position was changed from supine to head tilted down. Three minutes after the position change the refractive shift was stable in almost all eyes. Only slight changes in cylinder and the respective corresponding axis with a mean cylinder shift of 10.1 +/- 5.1 degrees were noted. Immediately after the head position was changed, aphakic eyes demonstrated more pronounced refractive shifts than phakic eyes. The results of this study explain patients' reports of diurnal changes in visual acuity after intraocular silicone oil instillation. Refractive changes caused by silicone oil stabilized a few minutes after a change in head position.

Silicone oil for recurrent vitreous hemorrhage in previously vitrectomized diabetic eyes.

To investigate the clinical course of vitrectomized patients with recurrent diabetic vitreous hemorrhage who were treated by revitrectomy with silicone oil (SO) as a hemostyptic tamponade. Fifteen patients with recurrent vitreous hemorrhage due to proliferative diabetic vitreoretinopathy were included in this retrospective study. All eyes had had at least one vitrectomy prior to use of SO and the retina was completely attached at any time before revitrectomy with SO instillation. Thirteen patients had a blind fellow eye. There were 6 males and 9 females (mean age 62.7 years, range 45-76 years). The mean duration of SO tamponade was 25.8 months (range 9-35 months). The average follow-up period was 30.4 months (range 20-48 months). Ten out of 15 eyes (66.6%) improved postoperatively, 9 eyes had a visual acuity of > or = 0.02 at the latest follow-up visit. Secondary glaucoma occurred in 4 eyes, leading to phthisis in 1 eye. All 5 phakic eyes developed a cataract. A revitrectomy combined with a long-term hemostyptic SO tamponade offers a chance for restoration of useful visual acuity in diabetic eyes with persistent vitreous-hemorrhage that fails to subside after cryocoagulation and vitrectomy without tamponade. Because of possible visual loss from secondary glaucoma related to intraocular SO this treatment should mainly be considered in patients with a blind fellow eye.