Prevention of lens opacification during diabetic vitrectomy

Lensectomy at the time of vitrectomy on diabetic patients markedly increases the risk of postoperative neovascular glaucoma, and is to be avoided when possible. We conducted a randomized prospective double-blind trial to determine if the addition of supplemental glucose to BSS Plus intraocular irrigating solution would lessen or prevent intraoperative lens opacification. Ten subjects received BSS Plus (glucose = 100 mg/dl); five (50%) developed intraoperative lens changes which interfered with the surgeon's view (three to an extent necessitating lensectomy). Ten subjects received glucose fortified BSS Plus (glucose = 400 mg/dl); none developed intraoperative lens changes (P less than 0.03, Mann-Whitney Rank). There was no statistically significant difference between the two study groups with respect to preoperative lens changes, infusion fluid volume, operative time, patient age, duration of diabetes, fasting blood glucose level, hemoglobin A1 level or lens clarity 5 months after surgery. We conclude that glucose fortification of BSS Plus significantly reduces intraoperative lens opacification during diabetic vitrectomy.     

Effect of Ca(2+)-free and Mg(2+)-free BSS Plus solution on the retinal pigment epithelium and retina in rabbits

PURPOSE: To determine whether intravitreal irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus (Alcon Laboratory, Fort Worth, Texas) solution alters the adhesiveness between the retinal pigment epithelium and the retina of rabbits. METHODS: Thirty-four eyes of 34 Dutch pigmented rabbits underwent lensectomy and vitrectomy. Subsequently, the vitreous cavity of 24 eyes was irrigated with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 10 or 20 minutes. The other 10 eyes were irrigated with BSS Plus solution for 20 minutes as controls. To determine the adhesiveness between the retinal pigment epithelium and retina, a retinal detachment was produced in 12 of the 34 eyes. The apical surface of the retinal pigment epithelium and the photoreceptor outer segments were examined by scanning electron microscopy. Retinal physiology was assessed by electroretinography and retinal morphology by light microscopy. RESULTS: After retinal detachment was produced, the number of cone sheaths on the apical surface of the retinal pigment epithelium after irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes (33 +/- 15, mean +/- SD) was significantly less than the number of cone sheaths on the apical surface of the retinal pigment epithelium of eyes after irrigation with BSS Plus solution for 20 minutes (120 +/- 50) or the number of cone sheaths on the apical surface of the retinal pigment epithelium of eyes after 10 minutes of irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution (115 +/- 49; P =.02). The b-wave amplitudes in the eyes irrigated with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes were depressed compared with the b-waves in eyes irrigated with BSS Plus solution for 20 minutes on the first postoperative day (P =.03). After the third postoperative day, there was no significant difference in the b-waves (P >.06). Light microscopy demonstrated no morphologic abnormalities after the use of both solutions. CONCLUSIONS: Intravitreal irrigation with Ca(2+)-free and Mg(2+)-free BSS Plus solution for 20 minutes altered the adhesion between the retinal pigment epithelium microvilli and retinal outer segments and made the creation of retinal detachment less traumatic. These results suggest that Ca(2+)-free and Mg(2+)-free BSS Plus solution may be of clinical value for the creation of an intentional retinal detachment for foveal translocation surgery.     

Intraocular irrigating solutions. A clinical study of BSS Plus and dextrose bicarbonate fortified BSS as an infusate during pars plana vitrectomy

PURPOSE: To compare the effect of Balanced Salt Solution Plus (BSS Plus, Alcon Laboratories, Fort Worth, Texas, USA) and fortified regular BSS on the cornea and lens, when used for continuous irrigation in pars plana vitrectomy (PPV) surgery. METHODS: Prospective, investigator masked, randomised study. Forty patients were randomly assigned to undergo PPV using BSS Plus (n=20) or fortified BSS (n=20) [regular BSS, fortified with 10.5 cc. of dextrose in water (D5W) and 13.1 cc. of 8.4% sodium bicarbonate]. Intraoperative features of the corneal epithelium, postoperative changes in the corneal endothelial cell denstiy (ECD) at 3 months, and clarity of the lens during surgery and postoperatively were evaluated. RESULTS: Intraoperative epithelial changes were similar in both groups with 7 (35%) of the cases having the epithelium removed in the BSS Plus group and 8 (40%) in the BSS fortified group (P=0.23). The mean differences in ECD (3 months versus preoperative) in the operated eyes when adjusted for changes in the control eye showed no difference with the type of BSS (P=0.98). Intraoperative lens changes were more significant (P=0.018) in the BSS fortified group. Postoperative lens status at 3 months was similar for both groups. Though there was a trend towards worse postoperative nuclear sclerosis change in the BSS fortified group, it was not significant (P=0.160). CONCLUSION: Standard BSS fortified with dextrose and bicarbonate is an efficacious infusion fluid during pars plana vitrectomy. Both solutions showed comparable effects on postoperative corneal endothelial cell density and corneal epithelial changes intraoperatively. BSS fortified has more lenticular changes intraoperatively than BSS Plus although no lens had to be removed in either group. The study implications are important since BSS fortified is significantly less expensive than BSS Plus.     

Effect of corneal wetting solutions on corneal thickness during ophthalmic surgery.

PURPOSE: To measure the changes in corneal thickness with wetting solutions used in ophthalmic surgery. SETTINGS: Ege University, School of Medicine, Department of Ophthalmology, Izmir, Turkey. METHODS: Thirty-one adult pigmented rabbits that weighed about 2.5 kg each were anesthetized with pentobarbital sodium. The rabbits were randomly divided into 3 groups to receive 3 wetting solutions: Group 1, Ringer's lactate; Group 2, balanced salt solution (BSS); and Group 3, BSS with glutation (BSS Plus). The solutions were dropped on the right cornea of the rabbits at a rate of 6.0 cc in 12 minutes using an intravenous infusion pump. Corneal thickness was measured by ultrasonic pachymetry before and after the procedure, and the between-group changes in corneal thickness were compared. RESULTS: The corneal thickness before and after the procedure was 361.27 microm +/- 19.3 (SD) and 380.00 +/- 25.0 microm, respectively, in Group 1 (P =.000); 372.10 +/- 18.8 microm and 388.60 +/- 24.1 microm, respectively, in Group 2 (P =.003); and 358.10 +/- 26.5 microm and 360.10 +/- 24.1 microm, respectively, in Group 3 (P =.316). CONCLUSION: As a corneal wetting solution, BSS Plus resulted in significantly fewer changes in corneal thickness than Ringer's lactate or BSS. This should be considered in cases involving long intraocular surgery.     

Oxygen tension in the rabbit lens and vitreous before and after vitrectomy

Oxygen is believed to be one of the potential causative agents for the development of nuclear cataract following vitrectomy. The aim of this study was to determine the partial pressure of oxygen (pO2) in different compartments of the rabbit eye, and to describe the changes following vitrectomy. Twenty-six rabbits (3.5-5.3 kg) were anesthetized and oxygen tension was probed using a fiber-optic oxygen sensor system (optode). A micromanipulator was employed to ascertain the exact position of the probe within the eye. Measurements were taken pre- and post-vitrectomy at several defined positions within the vitreous, the lens and the anterior chamber. Follow-up measurements were performed 2 and 8 weeks after vitrectomy. The contralateral eye served as a control. Measurements in the normal rabbit eye showed that oxygen tension in the globe is asymmetrical with the lowest pO2 in the nucleus of the lens (10.4 mmHg+/-3.0). The region of the lens near the posterior capsule has an oxygen tension close to the values of the vitreous directly behind the posterior capsule (12.4 mmHg+/-3.1). The highest pO2 within the posterior compartment of the eye was measured close to the retinal surface (40-l60 mmHg) depending on neighboring large vessels. The tension drops off rapidly to 20 mmHg some 0.5 mm from the retina. From that position to the posterior surface of the lens there is a shallow gradient of decreasing pO2. Immediately following vitrectomy the pO2 in the BSS replacement varied from ca. 90-140 mmHg, and decreased over approximately 30 min. to levels that were 2-3 times that of normal vitreous. Two weeks after vitrectomy the pO2 values in the lens were 2-3 times as high as in the control eye (p < 0.05). In addition there is no longer a gradient in the vitreous cavity, except close to the retina. Eight weeks after vitrectomy, pO2 levels in the lens were decreased but still remained higher than in the normal eye (13.83 mmHg+/-0.02). The pO2 gradient in the vitreous was not detectable anymore. Overall the results provide evidence that oxygen levels in the lens increase significantly after vitrectomy in rabbits. If this occurs in humans it may contribute to cataract formation following surgery.     

Biosynthesis of neopterin, sepiapterin, and biopterin in rat and human ocular tissues

Neopterin, sepiapterin, and biopterin synthesis by lens, retina, and ciliary body-iris of rat and human indicates pteridine formation from their precursor, GTP. The pteridine biosynthesis was higher in the retina (neopterin 422 +/- 27, 260 +/- 24; sepiapterin 135 +/- 12, 118 +/- 14; biopterin 76 +/- 10, 68 +/- 8 nanomoles/g soluble protein/hr, in rat and human, respectively) than in the ciliary body-iris and lens. The light-sensitive pteridines may protect eye tissues against the effects of sunlight in addition to their role in the hydroxylation of aromatic amino acids.     

Difference in clearance of intravitreal triamcinolone acetonide between vitrectomized and nonvitrectomized eyes

PURPOSE: To study the difference in clearance of intravitreal triamcinolone acetonide quantitatively between vitrectomized and nonvitrectomized eyes. METHODS: Eighty-four eyes of 42 rabbits were divided in 2 groups: 42 right eyes underwent standard pars plana vitrectomy (vitrectomized group), and 42 left eyes were not operated on (nonvitrectomized group). All eyes received intravitreal injections with 0.1 mL (0.3 mg) of triamcinolone acetonide. Every 12 eyes were obtained by killing 6 rabbits 1, 2, 4, 7, 12, 20, or 30 days after intravitreal injection. Each eye was enucleated and immediately frozen at -70 degrees C. The frozen vitreous was prepared for measuring the concentration of triamcinolone acetonide. Triamcinolone acetonide was quantified by high-performance liquid chromatography and ultraviolet absorbance detection. RESULTS: After 30 days, triamcinolone acetonide was detected only in 1 eye (0.22 microg/mL) in the vitrectomized group compared with 4 of 6 eyes (0.92 +/- 1.25 microg/mL) in the nonvitrectomized group. The coefficient of logarithmic regression was -0.12 in the vitrectomized group and -0.08 in the nonvitrectomized group. Triamcinolone acetonide decreased 1.5 times more rapidly in the vitrectomized group than in the nonvitrectomized group. The half-life of triamcinolone acetonide was 1.57 days in the vitrectomized group and 2.89 days in the nonvitrectomized group. CONCLUSION: Intravitreal triamcinolone acetonide decreases more rapidly in the vitrectomized eye than in the nonvitrectomized eye. Therefore, the faster clearance of intravitreal triamcinolone acetonide must be considered when planning intravitreal injection of triamcinolone acetonide in the vitrectomized eye.     

Effect of lipid-hydroperoxide-induced oxidative stress on vitamin E, ascorbate and glutathione in the rabbit retina

BACKGROUND: It is possible that oxidative stress causes several retinal diseases. However, the natural biogenic role of antioxidants in the retina is not clear. PURPOSE: This study investigates the change in concentration of vitamin E (VE), ascorbate and glutathione (GSH) in the retina following vitreous injection of 600 mug 18:2 linoleic acid hydroperoxide (LHP) in male New Zealand rabbits. METHOD: LHP was injected above the retinal surface. The animals were sacrificed and the eyes enucleated before LHP injection, 1, 3, 6, 12, 24 h and 4 and 7 days after LHP injection. Retinas were removed, VE and ascorbate measured by HPLC, and GSH determined by a fluorometric method. RESULTS: The concentration of VE in the retina decreased from pretreatment levels of 154.6 +/- 29.7 nmol/g wet weight (n = 7) and was lowest at 6 h (61.1 +/- 18.1 nmol/g wet weight, n = 4, p < 0.05), then increased gradually, returning slowly to pre-LHP levels by 7 days. The concentration of ascorbate in control retinas decreased at 6 h from pretreatment levels of 7.33 +/- 0.93 micromol/g wet weight (n = 7) to 2.74 +/- 0.16 micromol/g wet weight (n = 4, p < 0.05) and returned to pretreatment levels rapidly by 24 h after injection. The concentration of GSH in retinas decreased from baseline levels of 109.53 +/- 8.19 microg/g wet weight (n = 9), was lowest at 12 h (72.40 +/- 11.17 microg/g wet weight, n = 5, p < 0.05) and returned to pretreatment levels by 7 days. CONCLUSION: The results suggest that intravitreous LHP injection is a contributor to oxidative stress in the rabbit retina by causing a reduction in antioxidant capacity.     

灌注液对糖尿病玻璃体切割手术中角膜内皮的影响

目的 评价不同灌注液对糖尿病玻璃体切割手术中角膜内皮细胞的影响。方法 对30例术中应用BSS或BSSPlus的糖尿病玻璃体切割手术眼的角膜内皮细胞密度和细胞面积变异系数进行前瞻性研究．结果 无囊膜组中应用BSSPlus的玻切手术眼角膜内皮细胞密度、细胞面积变异系数与应用BSS的手术眼之间存在明显差异，在有囊膜组中二者之间无明显差异。结论 对于囊膜不完整的糖尿病患者玻切手术中使用BSSPlus可减轻手术对角膜内皮细胞的损害。     

Effects of subretinal injection of patent blue and trypan blue in rabbits

PURPOSE: To investigate the histologic and clinical effects of subretinal injection of patent blue (PB) and trypan blue (TB) in rabbits. METHODS: Dutch-belted rabbits (n=8) were vitrectomized followed by subretinal injection of 2.4 mg/ml PB (285 mOsm) and 1.5 mg/ml TB (312 mOsm); balanced salt solution (BSS) (300 mOsm) served as the control. Animals were examined 6, 12, and 24 hr and 14 days after the procedure by fluorescein angiography (FA) and indirect ophthalmoscopy; for retinal toxicity, histologic evaluation studies were performed by light and transmission electron microscopy. RESULTS: FA examination demonstrated window defects suggestive of retinal pigment epithelium (RPE) atrophy in positions of subretinal TB injection, but this was not observed after subretinal injection of PB or BSS. Histologic evaluation disclosed only minimal abnormalities on the photoreceptor outer segment (POS) after subretinal injection of BSS during all follow-up. Subretinal injection of PB caused POS and photoreceptor inner segment (PIS) abnormalities 12 and 24 hr after surgery as well as outer nuclear layer (ONL) damage 14 days after surgery. Subretinal TB injection resulted in POS and PIS damage at 12 hr follow-up. The ONL damage was observed 24 hr after surgery; additionally, POS, PIS, ONL, and RPE abnormalities were observed 14 days after surgery after TB injection. CONCLUSIONS: Subretinal injection of TB induced more significant clinical and histologic damage of neurosensory retina/RPE than did PB or BSS. Future human studies are necessary to access the clinical relevance of these in vivo experiments.     

Vitrectomy prevents retinal hypoxia in branch retinal vein occlusion

Vitrectomy has been shown to halt diabetic retinal neovascularization, but the mechanism of this process is unknown. We propose that vitrectomy improves the oxygen supply to ischemic inner retina by way of fluid currents in the vitreous cavity. In order to test this hypothesis, we induced branch retinal vein occlusion in cats and measured preretinal oxygen tension before and after branch retinal vein occlusion in ten nonvitrectomized and five vitrectomized eyes. Branch retinal vein occlusion caused a significant decrease in preretinal oxygen tension in nonvitrectomized eyes, in which the oxygen tension fell from 20 +/- 7 to 6 +/- 5 mmHg (P = 0.001). Conversely, in vitrectomized eyes the oxygen tension was not significantly reduced after branch retinal vein occlusion. The data demonstrate that branch retinal vein occlusion causes retinal hypoxia in nonvitrectomized eyes, whereas after vitrectomy the hypoxic effect of branch retinal vein occlusion is reduced. The relief of retinal hypoxia that follows vitrectomy may be responsible for halting retinal neovascularization after vitrectomy in diabetic patients.     

Intraocular ciprofloxacin levels after oral administration in silicone oil-filled eyes

PURPOSE: To evaluate penetration of oral ciprofloxacin in the retro-silicone oil space fluid (RSOF) in silicone oil (SO)-filled eyes. METHODS: One dose of 750 mg ciprofloxacin was given to two groups of five patients with vitrectomized eyes with SO endotamponade, 4 hours (group I) and 8 hours (group II) before SO removal. In 10 vitrectomized eyes with SO endotamponade (group III) and another 10 patients scheduled for vitrectomy for the first time (group IV), two 750-mg doses every 12 hours, with the last dose 12 hours before surgery, were given. Blood samples were taken at the time of collection of RSOF samples in groups I, II, and III and of the vitreous in group IV. All samples were assayed for ciprofloxacin by high-performance liquid chromatography. RESULTS: The mean drug concentration in the RSOF was 0.34 +/- 0.09, 0.37 +/- 0.04, 0.84 +/- 0.29, and 0.44 +/- 0.11 micro g/mL in groups I, II, III, and IV respectively. The mean serum concentration was 1.29 +/- 0.63, 1.08 +/- 0.14, 1.93 +/- 0.84, and 1.34 +/- 0.55 micro g/mL in groups I, II, III, and IV respectively with no statistically significant difference between groups III and IV (P = 0.081). CONCLUSIONS: Antibiotic levels in the RSOF in SO-filled eyes after oral administration of ciprofloxacin in two 750-mg doses exceeded the minimal inhibitory concentration for 90% of isolates (MIC(90)) for most bacterial species and was higher than levels reached in the vitreous in nonvitrectomized eyes (P = 0.001).     

Vitrectomy does not increase the risk of open-angle glaucoma or ocular hypertension—a 5-year follow-up

Background

The goal of this study was to investigate the development of late onset open-angle glaucoma (OAG) or ocular hypertension after vitrectomy in phakic and pseudophakic eyes.

Methods

In this retrospective case series, the records of 441 patients who had undergone vitrectomy in one eye by a single surgeon were reviewed. The development of OAG or ocular hypertension in the vitrectomized and fellow control eyes was compared. Furthermore, the influence of the lens status (phakic or pseudophakic) on the onset of OAG or ocular hypertension in the vitrectomized and fellow control eyes was analysed. Additionally, the mean intraocular pressure (IOP) and the mean number of antiglaucomatous medications were calculated for both eyes.

Results

A mean follow-up period of 79.5?±?25.6 months was achieved. There were 19 vitrectomized eyes (4.31%) with postoperative OAG, and 19 vitrectomized eyes (4.31%) with postoperative ocular hypertension. Eleven control eyes (2.49%) had OAG, and 13 control eyes (2.95%) ocular hypertension. There were no statistically significant differences in the development of OAG or ocular hypertension between the vitrectomized and fellow control eyes. Furthermore, the lens status in vitrectomized eyes did not influence the late development of OAG or ocular hypertension. There were no significant differences in the mean IOP and the mean number of antiglaucomatous medications between the two eyes.

Conclusions

Contrary to previous reports, we could not observe an increased incidence of late onset OAG or ocular hypertension after vitrectomy. Similarly, the removal of the lens did not increase the risk of OAG or ocular hypertension in vitrectomized eyes.     

TPA-assisted vitrectomy for proliferative diabetic retinopathy: results of a double-masked, multicenter trial.

OBJECTIVE: Some complications of vitrectomy are related to adherence of the vitreous body to the retina. We studied whether these complications could be decreased by injecting a proteolytic enzyme, tissue plasminogen activator (TPA), at the beginning of surgery to aid separation of the vitreous from the retina. METHODS: Fifty-six patients receiving surgery for complications of proliferative diabetic retinopathy were divided into two groups in this prospective, randomized, double-blind study. Group I patients received 25 microg of intravitreal TPA in buffered salt solution (BSS) 15 minutes before vitrectomy. Group II received BSS alone. Postoperative follow-up lasted up to 3 months. The major criteria for comparison were the number of perioperative iatrogenic tears, the gain in visual acuity, and the reattachment rate of tractional retinal detachments. RESULTS: No difference was found between the two groups for the principal indicators or for complications. CONCLUSION: In proliferative diabetic retinopathy, the use of 25 microg of TPA by intravitreal injection 15 minutes before vitrectomy does not improve the results. No specific complications of the method were noted. The failure can be attributed to a too-short delay between TPA injection and beginning of surgery, an insufficient dose, or an insufficient quantity of plasminogen in the vitreous at the beginning of the intervention.     

Phacoemulsification and pars plana vitrectomy: a combined procedure

AIM: To describe the results of a combined procedure including phacoemulsification, insertion of posterior chamber intraocular lens (PCIOL) and pars plana vitrectomy (PPV) in eyes with vitreoretinal pathology and coexisting significant cataract. DESIGN: Retrospective, consecutive, noncomparative, interventional case series. MATERIALS AND METHODS: Medical records of patients who had undergone phacoemulsification, PPV and PCIOL implantation as a combined procedure between January 2000 and December 2004 were retrospectively reviewed. The main outcome measures were the anatomical success of retina, defined as reattached retina, intraoperative and postoperative complications and functional success in terms of final best corrected visual acuity. RESULTS: In all, 65 eyes of 64 patients were included. The mean age of the patients was 50.9 years +/- 17.1 (range, five to 82 years). Vitreous hemorrhage with or without retinal detachment (19 eyes, 29.2%) was the most common indication for the vitreoretinal procedure. Primary anatomical success of retina was achieved in 59 eyes (90.7%). Visual acuity improved in 48 eyes (73.8%), was unchanged in 12 eyes (18.5%) and deteriorated in five eyes (7.7%). Postoperative inflammation was significantly more in the subgroup of previously vitrectomized eyes (42%) (P =0.014, Fisher exact test) compared to those which underwent primary vitrectomy. CONCLUSIONS: Combined surgery is a feasible option for patients with vitreoretinal diseases and cataract.     

Evaluation of the results of cataract extraction and lends implantation in eyes after vitrectomy

PURPOSE: To evaluate the results of cataract surgery in previously vitrectomized eyes. MATERIAL AND METHODS: In 41 eyes, that had undergone prior vitrectomy, extracapsular cataract extraction was done and intraocular lens was implanted. The average time between operations was 14.5 months (range from 2 months to 6 years). The mean follow-up was 19 +/- 12.2 months (range from 4 months to 4 years). RESULTS: Statistically significant improvement was observed in visual acuity after cataract extraction and IOL implantation, compared to the results after vitrectomy. The most frequent complication was posterior capsule opacification, which occurred in 9 eyes (22%). CONCLUSIONS: The results show, that intraocular lens implantation in eyes after vitrectomy is safe and achieved visual acuity is similar or better, than before cataract formation.     

Induction of posterior vitreous detachment in rabbits by intravitreal injection of tissue plasminogen activator following cryopexy

The purpose of this study was to generate intravitreal plasmin after intravitreal injection of tissue plasminogen activator (TPA) and cryopexy, and to assess its proteolytic effect on the vitreoretinal border region.Twenty-four hr after a mild cryopexy, 25 microg recombinant tissue plasminogen activator (TPA) was injected into the vitreous cavity, the fellow eye received an intravitreal injection of the same volume of buffered salt solution. Light, scanning and transmission electron microscopy was performed in 24 eyes that underwent vitrectomy 1 week later. Plasmin was measured prior and 2 hr after intravitreal TPA injection (4 eyes). Hyaluronic acid (8 eyes) and vitronectin (4 eyes) were measured 1 week after TPA- or BSS-injection and compared to untreated controls.In all eyes treated with TPA, histopathologic examination by scanning and transmission electron microscopy demonstrated a complete detachment of the vitreous from the surface of the retina as well as from the posterior surface of the lens. After BSS-injection, vitreous cortex attachment to the retina was demonstrated in all eyes. Two hr after TPA-injection, plasmin increased to 9.75 mU ml(-1)(s.d.+/-2.3). Neither a decrease of hyaluronic acid nor an increase of transglutaminase, that might alter the vitreous structure leading to a collapse of the vitreous, were detected in treated eyes. There was no increase of vitronectin indicating proliferative activity.A temporary breakdown of the blood-retinal barrier by cryopexy combined with intravitreal injection of TPA is a sufficient technique to induce a posterior vitreous detachment enzymatically. The method may be useful prior to mechanical vitrectomy.     

Effects of intraocular irrigants on the preserved human corneal endothelium

Either a simple balanced salt solution (BSS) or a bicarbonate-buffered, glutathione-containing commercial irrigant (BSS Plus, Alcon Laboratories, Fort Worth, Texas, U.S.A.) may be used during the vitrectomy portion of a corneal transplant procedure. To simulate the conditions present in the anterior chamber during the first few hours after vitrectomy and grafting, we performed in vitro perfusions of stored human corneas using each irrigant and measured corneal thickness over a 3-hour period. Irrespective of the preservation medium used (McCarey Kaufman, Chondroin Sulfate or Dexsol, all from Chiron Ophthalmics, Irvine, California) or duration of storage (2 or 4 days), corneas irrigated with BSS Plus exhibited significantly (p less than .05) decreased thickness compared with their paired mates irrigated with BSS. In ultrastructural studies performed on postperfusion corneas, there was a tendency toward improved surface morphology in the in vitro BSS Plus-perfused tissue. This study shows that in vitro corneal thickness after preservation is significantly irrigant dependent, with BSS Plus providing the essential ingredients to promote the corneal endothelial pump function.     

Comparison of intraocular irrigating solutions used for pars plana vitrectomy and prevention of endothelial cell loss

We performed a prospective study of corneal endothelial cell loss following pars plana vitrectomy. Two different intraocular irrigating solutions were used, and the anterior capsule of the lens was removed when performing lensectomy. The central corneal endothelium was photographed with a specular microscope before and at three months after vitrectomy. Endothelial cell loss was calculated using a computer-assisted digitizer. In the 16 aphakic eyes, lactated Ringer's solution caused a significantly greater cell loss (31.1%) with resultant corneal edema when compared to BSS Plus (6.9%). All of the 17 phakic eyes showed minimal cell loss (1.0%) as well as corneal changes regardless of the kind of irrigating solution used. The results suggest that the absence of the lens is a salient factor in corneal endothelial damage during vitrectomy, and that the composition of the intraocular solution used is closely related to this endothelial damage.     

Intraocular irrigating solutions and vitrectomy-related changes (in protein, lactic and ascorbic acid) in rabbit vitreous.

Vitrectomy and the subsequent vitreous fluid exchange alter the chemical and physical properties of the vitreous. This study assessed the time course alterations of total protein, ascorbic acid and lactic acid in the rabbit vitreous cavity following vitrectomy. Normal values were 2.2 +/- 1.2 mg/ml, 8.5 +/- 1.0 mg/100 ml and 16.8 +/- 3.5 mumol/ml, respectively. Nine groups of 5-10 adult albino rabbits underwent closed vitrectomy using physiologic saline, Ringer's lactate and BSS plus solutions. Samples were withdrawn at 3 and 24 h and 7 days after vitrectomy. Total protein levels increased in all groups at 3 and 24 h (20-30 mg/ml). Ascorbic acid measurements at 24 h rose only with saline and BSS plus. At 24 h the BSS plus group was the only one demonstrating an increased lactic acid concentration.