Air-filled Eye Research Articles

Tono-pen and Schiotz tonometer measurements in gas-filled eyes

This study aims to assess the difference between Tono-Pen and Schiotz tonometer measurements in gas-filled eyes and to create a nomogram and equation which can be used to estimate actual intraocular pressure in order to provide a safe IOP level at the end of the surgery. Twenty-two eyes that underwent pars plana vitrectomy were included in the study. Perioperative Tono-Pen and Schiotz tonometer measurements were performed when the eyes were filled with air in the setting of certain vitrectomy infusion pressure levels. Measurements were performed when the eyes were filled with fluid to test the accuracy of the systems. The mean value of the Tono-Pen and Schiotz readings in air-filled eyes corresponding to certain actual intraocular pressure levels were analyzed to create nomograms. Both Tono-Pen and Schiotz tonometers underestimated the actual intraocular pressure set on the screen of the vitrectomy system in the air-filled eyes. The Tono-Pen deviation was 4.5mmHg at a level of 15mmHg actual intraocular pressure, and 16.9mmHg at a level of 55mmHg actual intraocular pressure. The Schiotz tonometer deviation was 10mmHg at a level of 15mmHg actual intraocular pressure, and 8.9mmHg at a level of 55mmHg actual intraocular pressure. All the mean differences between tonometer readings and actual intraocular pressure were statistically significant. (P<0.001) CONCLUSION: To achieve an adequate and safe tamponade at an actual IOP range of 20 - 25mmHg, one should adjust the IOP with Schiotz readings to a level of 9-12mmHg, or Tono-Pen readings to 12-18mmHg.

Case report: Biometry in air-filled eye following retinal surgery

A 70-year-old male patient presented with vitreous hemorrhage in his right eye, for which he was advised for pars plana vitrectomy and endolaser. During the surgery, there was inadvertent contact with the crystalline lens with one of the intraocular instruments. This was reported as an intraocular complication. Postoperatively, cataract was developed in his right eye due to lens touch. An early cataract surgery was planned. A scan was done in phakic eye on day three after first surgery, which showed axial length 28.7 mm. On the postoperative day 10, axial length was 22.25 mm using contact method. Surgery was delayed for 4–5 days due to this. No A Scan machine has software for axial length and correct lens power calculation in air-filled eyes following retinal surgeries. A scan machine does not have information or software to calculate intraocular lens power in air-filled eyes after retinal surgery. This information will be helpful in planning early cataract surgeries if required after retinal surgery.

Surgical outcomes of 27-gauge and 25-gauge vitrectomy day surgery for proliferative diabetic retinopathy

To compare postoperative outcomes of 27-gauge (G) and 25-G vitrectomy conducted as day surgery for proliferative diabetic retinopathy (PDR). One hundred eighty-five consecutive PDR patients (185 eyes) who underwent primary vitrectomy (27-G in 64 eyes, 25-G in 121 eyes) were analyzed. The 27-G and 25-G groups did not differ significantly in preoperative Early Treatment Diabetic Retinopathy Study (ETDRS) score, age, or preoperative intraocular pressure. The proportions of simultaneous cataract surgery (27-G vs. 25-G: 59.4% vs. 62.4%) and air-filled eyes (76.6% vs. 85.1%) were not significantly different between two groups. Both groups showed significant improvement in ETDRS score at postoperative 1, 3, and 6months (all, P < 0.0001). Mean gain in ETDRS score from baseline was apparently better in 27-G group than in 25-G group at 1, 3, and 6months, but there were no significant differences (1month: 20.3 vs. 13.1 letters, P = 0.0703; 3months: 22.9 vs. 17.5 letters, P = 0.1561; 6months: 24.3 vs. 19.3 letters, P = 0.3313). Operation time was apparently longer for 27-G vitrectomy, but there was no significant difference (54.0 vs. 51.1min, P = 0.3676). The same was observed for postoperative intraocular pressure at postoperative day 1 (19.7 vs. 18.1mmHg, P = 0.1353). Incidence of postoperative retinal detachment (1.6% vs. 0.8%) and reoperation due to vitreous hemorrhage (6.3% vs. 6.6%) was not different between two groups. The 27G system is as safe and as usefulas the 25G system when used for PDR and can be expected to achieve earlier recovery of postoperative visual acuity.

Air tamponade in retinal detachment surgery followed by ultra-widefield fundus imaging system

To report the surgical result of pars plana vitrectomy (PPV) with air tamponade for rhegmatogenous retinal detachment (RRD) by ultra-widefield fundus imaging system. Of 25 consecutive patients (25 eyes) with fresh primary RRD and causative retinal break and vitreous traction were presented. All the patients underwent PPV with air tamponade. Visual acuity (VA) was examined postoperatively and images were captured by ultra-widefield scanning laser ophthalmoscope system (Optos). Initial reattachment was achieved in 25 cases (100%). The air volume was >60% on the postoperative day (POD) 1. The ultra-widefield images showed that the retina was reattached in all air-filled eyes postoperatively. The retinal break and laser burns in the superior were detected in 22 of 25 eyes (88%). A missed retinal hole was found under intravitreal air bubble in 1 case (4%). The air volume was range from 40% to 60% on POD 3. A double-layered image was seen in 25 of 25 eyes with intravitreal gas. Retinal breaks and laser burns around were seen in the intravitreal air. On POD 7, small bubble without effect was seen in 6 cases (24%) and bubble was completely disappeared in 4 cases (16%). Small oval bubble in the superior area was observed in 15 cases (60%). There were no missed and new retinal breaks and no retinal detachment in all cases on the POD 14 and 1mo and last follow-up. Air disappeared completely on a mean of 9.84d postoperatively. The mean final postoperative best-corrected visual acuity (BCVA) was 0.35 logMAR. Mean final postoperative BCVA improved significantly relative to mean preoperative (P<0.05). Final VA of 0.3 logMAR or better was seen in 13 eyes. PPV with air tamponade is an effective management for fresh RRD with superior retinal breaks. The ultra-widefield fundus imaging can detect postoperative retinal breaks in air-filled eyes. It would be a useful facility for follow-up after PPV with air tamponade. Facedown position and acquired visual rehabilitation may be shorten.

27-gauge and 25-gauge vitrectomy day surgery for idiopathic epiretinal membrane

BackgroundThis study compared the postoperative outcomes of 27-gauge (G) and 25-G vitrectomy performed for the treatment of idiopathic epiretinal membrane (ERM).MethodsThe study design was single center, retrospective, interventional case series. Two hundred consecutive eyes that underwent primary vitrectomy for ERM (27-G vitrectomy in 100 eyes and 25-G vitrectomy in 100 eyes) were studied for 6 months. In all eyes, scleral tunnels were made using angle incisions, and air or gas exchange was performed.ResultsThere were no significant differences in age, spherical diopter power, as well as preoperative Early Treatment Diabetic Retinopathy Study (ETDRS) score, central retinal thickness (CRT), and intraocular pressure between the 27-G and 25-G groups. The proportions of simultaneous cataract surgery (27-G vs. 25-G: 82% vs. 90%), air-filled eyes (99% vs. 98%), and scleral wound suture at the end of surgery (0% vs. 0%) were not significantly different between two groups. The mean operation time for vitrectomy was significantly (P = 0.0322) longer by 4 min for 27-G (37 min) compared to 25-G (33 min) vitrectomy. Gain in ETDRS score was significantly (P = 0.0421) better in 27-G group (4.7 ± 8.1 letters) compared to 25-G group (1.1 ± 13.6 letters) at 1 month post-vitrectomy, but not significantly different at 3 and 6 months (P = 0.0835 and 0.0569, respectively). Decrease in CRT was significantly (P = 0.0354) greater in 27-G group (−24.2 ± 50.0 μm) compared to 25-G group (−8.0 ± 48.6 μm) at 1 month post-vitrectomy, but not significantly different at 3 and 6 months (P = 0.6059 and 0.1725, respectively). On postoperative day 1, hypotony (≤ 6 mmHg) was observed in 2 eyes in 27-G group and 6 eyes in 25-G group, while ocular hypertension (≥ 25 mmHg) was found in 4 eyes in 27-G group and 11 eyes in 25-G group, with no significant differences between two groups. Postoperative complications requiring treatment occurred in one eye (vitreous hemorrhage) in 27-G group, and in two eyes (vitreous hemorrhage and retinal detachment in one eye each) in 25-G group.ConclusionsAlthough 27-G vitrectomy requires operation time of 4 min longer compared to 25-G vitrectomy for ERM surgery, using the 27-G system results in earlier recovery of visual acuity, CRT improvement and stabilized ocular pressure.

Analysis of the intraocular jet flows and pressure gradients induced by air and fluid infusion: mechanism of focal chorioretinal damage.

To comprehend the mechanism of focal chorioretinal damage by analysis of the pressure distribution and dynamic pressure induced by infused air during fluid-air exchange. A precise simulation featuring a model eye and a fluid circuit was designed to analyze fluid-air exchange. The pressure distribution, flow velocity, and dynamic pressure induced by infusion of air into an air-filled eye were analyzed using an approach based on fluid dynamics. The size of the port and the infusion pressure were varied during simulated iterations. We simulated infusion of an air-filled eye with balanced salt solution (BSS) to better understand the mechanism of chorioretinal damage induced by infused air. Infused air was projected straight toward a point on the retina contralateral to the infusion port (the "vulnerable point"). The highest pressure was evident at the vulnerable point, and the lowest pressure was recorded on most retinal areas. Simulations using greater infusion pressure and a port of larger size were associated with elevations in dynamic pressure and the pressure gradient. The pressure gradients were 2.8 and 5.1 mm Hg, respectively, when infusion pressures of 30 and 50 mm Hg were delivered through a 20-gauge port. The pressure gradient associated with BSS infusion was greater than that created by air, but lasted for only a moment. Our simulation explains the mechanism of focal chorioretinal damage in numerical terms. Infused air induces a prolonged increase in focal pressure on the vulnerable point, and this may be responsible for visual field defects arising after fluid-air exchange.

Intraoperative assessment of intraocular pressure in vitrectomized air-filled and fluid-filled eyes

To ascertain the difference of intraocular pressure (IOP) measurement between vitrectomized air-filled and fluid-filled eyes. Thirty-one eyes of 31 consecutive patients who underwent conventional vitrectomy and intraocular gas tamponade were assessed. After vitrectomy, IOP of the fluid-filled eyes was measured by Tono-Pen. Thereafter, fluid-air exchange was performed, and IOP of the air-filled eyes was measured again. The IOP within each fluid- and air-filled eye was varied by selecting settings on the vitrectomy system, from 10 to 50 mmHg with 5-mmHg increments. Postoperatively, IOP was assessed by both Tono-Pen and Goldmann applanation tonometry (GAT). Linear and nonlinear regression analyses were conducted between intraoperatively measured Tono-Pen readings and actual IOPs. Bland-Altman plot was used to assess the agreements between postoperatively measured Tono-Pen readings and GAT readings. The discrepancy between Tono-Pen readings and actual IOP in fluid-filled eyes was not significant, except for the profound high pressures over 45 mmHg. However, Tono-Pen readings in air-filled eyes were significantly lower than actual IOPs in all ranges, and Tono-Pen increasingly underestimates IOP at higher levels. Intraoperative Tono-Pen readings were correlated significantly with actual IOP and a quadratic equation evidenced the best fit (R(2) = 0.996). Postoperatively, difference of the measurements between Tono-Pen and GAT was not significant. Tono-Pen and GAT significantly underestimate actual IOP in air-filled eyes. It should be considered that actual IOP would be greater than the measured IOP in gas-filled eyes, even though the IOP is measured as normal.

STUDY OF INTRAOCULAR PRESSURE AFTER 23-GAUGE AND 25-GAUGE PARS PLANA VITRECTOMY RANDOMIZED TO FLUID VERSUS AIR FILL

To determine if a difference in intraocular pressure (IOP) exists after small-gauge pars plana vitrectomy randomized to fluid versus 80% sterile air fill. Ninety-two eyes undergoing 23-gauge and 25-gauge transconjunctival pars plana vitrectomy were randomized to fluid versus air fill, and IOP was measured at 5 different time points. There is no difference in the mean IOP for eyes undergoing small-gauge pars plana vitrectomy randomized to fluid versus air fill after vitrectomy. Using 23-gauge instrumentation, the mean immediate and 2-hour postoperative IOPs were statistically lower than the mean preoperative IOP. The mean Postoperative Day 1 and Week 1 IOPs were statistically higher than the mean immediate postoperative IOP. Using 25-gauge instrumentation, the mean IOP was not statistically different at any time points in the 2 groups. When comparing 23-gauge with 25-gauge instrumentation, the immediate postoperative IOP was statistically lower and the rate of suture closure for sclerotomies was higher for 23-gauge vitrectomy. When performing 23-gauge or 25-gauge pars plana vitrectomy, there was no difference in mean IOP for fluid- versus air-filled eyes. However, the mean IOP in the immediate postoperative period was statistically lower, and there was a higher rate of suture closure for 23-gauge compared with 25-gauge instrumentation.

Pupillary Block Glaucoma After Pars Plana Vitrectomy with Air-Fluid Exchange in Pseudophakic Air-Filled Eye.

Pupillary block is seen after pars plana vitrectomy (PPV) with gas or silicone oil endotamponade in aphakic eyes. A case of a pseudophakic patient with pupillary block glaucoma related to the migration of air into the anterior chamber was reported. A 76-year-old woman underwent combined PPV with air endotamponade and uncomplicated cataract extraction for epiretinal membrane and cataract. On postoperative day 1, she had an 80% air fill of the anterior chamber. She returned 6 days later with pupillary block glaucoma. She was managed with a surgical peripheral iridectomy, posterior synechiolysis, and evacuation of the air from the anterior chamber. The risk of pseudophakic pupillary block glaucoma after PPV with air tamponade may be increased with inflammation due to combined PPV and cataract extraction, zonular weakness, and efflux of air from the vitreous cavity into the anterior chamber. Early detection and treatment is recommended to avoid permanent sequelae.

Einfluss von Vitalfarbstoffen auf die Funktion der äußeren Blut-Retina-Schranke in vitro

The use of vital dyes in "chromovitrectomy" allows the easier removal of less recognizable structures like epiretinal membranes (EM) or the inner limiting membrane (ILM). In recent years numerous studies demonstrated the use of indocyanine green (ICG), trypan blue (TB) and patent blue (PB) for this indication. Reports of the possible risk of these dyes, i. e. especially ICG, in respect of reduced visual acuity results, possible visual field defects or alterations of the retinal pigment epithelium (RPE) resulted in limitations in their application. Human RPE cells and choroidal endothelial cells were cultured in monolayers on semipermeable membranes representing an in vitro model of the outer blood-retinal barrier. By measurement of the transepithelial electrical resistance (TER) the stable barrier function was determined. Two different models representing an air-filled and a fluid-filled eye were tested on the one hand by addition of the dye to the culture medium and, on the other, by direct application on the cell monolayer. In these two models ICG (5 mg/ml, 0.5 mg/ml, 0.125 mg/ml), TB (1.5 mg/ml, 0.15 mg/ml) and PB (2.4 mg/ml, 0.24 mg/ml) were applied for three minutes and the influence on the barrier function was determined. RPE cell growth was also tested in these two models after the application of ICG, TB and PB. Finally, monolayers of RPE cells were evaluated by transmission electron microscopy (TEM). After application of TB, PB and the lowest concentration of ICG of 0.125 mg/ml, the TER remained stable in both models. In contrast, ICG in a concentration of 5 mg/ml and 0.5 mg/ml caused a significant TER decrease in the model of the air-filled eye, whereas no influence on the function of the outer blood-retinal barrier was noted in the model of the fluid-filled eye. RPE cell growth rates were not influenced by the addition of the vital dyes, with the exception of ICG in a concentration of 5 mg/ml in the model of the air-filled eye, resulting in a temporary reduction of the cell count. In good correspondence to these results also in TEM intercellular blisters were noted after application of 5 mg/mL ICG for 3 minutes in the model of the air-filled eye. However, damage to the RPE cells themselves was not obvious. No pathological changes in the TEM were noted after application of TB and PB. The use of PB and TB at the posterior eye segment seems to be safe concerning damage to the PRE and its barrier function. In contrast, ICG in higher concentrations and with longer application times may cause a toxic effect on RPE morphology and function.

EFFECTS OF INDOCYANINE GREEN ON THE RETINA AND RETINAL PIGMENT EPITHELIUM IN A PORCINE MODEL OF RETINAL HOLE

This study was designed to emulate human macular hole surgery and to test the effects of indocyanine green (ICG) on the retina and retinal pigment epithelium (RPE). Yorkshire Cross pigs (n = 23) underwent vitrectomy, separation of the posterior cortical vitreous, and creation of a single retinal hole. In three study groups (n = 6, each group), air-fluid exchange was performed, following which balanced salt solution (BSS), 1.0% ICG, or 0.5% ICG was applied over the retinal hole. In one additional group (n = 5), 0.5% ICG was injected into the fluid-filled eye. At 4 weeks, the eyes were examined clinically, and fundus photographs were obtained before enucleation and light microscopic examination. Clinical evaluations documented a statistically significant difference between study groups (P = 0.036). There was a higher rate of moderate or severe RPE atrophy among animals where 1% or 0.5% ICG was applied in air-filled eyes (83% and 67%, respectively) compared with BSS controls (17%) and fluid-filled eyes receiving 0.5% ICG (40%). Histologic evaluation demonstrated a statistically significant difference between groups (P = 0.044), with extensive outer retinal degeneration observed in air-filled eyes receiving 1% or 0.5% ICG (66% and 60%, respectively) compared with BSS controls or fluid-filled eyes receiving 0.5% ICG (none of the eyes in either group). None of the study groups had any changes in the inner retina except at the retinal hole site. Retina exposed to ICG concentrations used in human vitreoretinal surgery had greater RPE atrophy and outer retinal degeneration than control eyes undergoing the same surgery without ICG. Eyes filled with infusion fluid during ICG injection had less damage to the RPE and outer retina than did air-filled eyes receiving ICG.

Vitreoretinal surgery through multifocal intraocular lenses compared with monofocal intraocular lenses in fluid-filled and air-filled rabbit eyes

Purpose To compare vitrectomy procedures and visualization of posterior segment structures through multifocal silicone intraocular lenses (IOLs) with the same procedures through monofocal silicone IOLs in rabbit eyes. Design Experimental study. Participants Twelve eyes of six rabbits. Methods Each rabbit eye underwent phacoemulsification of the lens and posterior chamber implantation of a silicone multifocal or silicone monofocal IOL. The type of IOL (monofocal vs. multifocal) implanted in the first eye of each rabbit was randomly decided. The fellow eye then received the other IOL type. Vitrectomy procedures were performed through the IOLs by using a flat contact lens (part 1) or wide-angled contact lens (part 2) for visualization through fluid-filled (parts 1 and 2) and air-filled (part 2) eyes. Main outcome measures Image quality, stereopsis, and contrast were subjectively graded on a scale of 0 (none) to 4 (excellent) for each eye by each surgeon. Results In part 1, image quality averaged 4 for the monofocal IOL and 3.6 for the multifocal IOL. Stereopsis averaged 4 for the monofocal IOL and 4 for the multifocal IOL. Contrast averaged 4 for the monofocal IOL and 3.9 for the multifocal IOL. Vitrectomy with retinal surface maneuvers was successfully performed in both pigmented and nonpigmented rabbit eyes through both IOL types. In part 2, image quality, stereopsis, and contrast were rated as 4 for both multifocal and monofocal silicone IOLs. Air-fluid exchange was performed without difficulty. Image quality, stereopsis, and contrast were rated as 4 for air-filled eyes. Conclusions Visualization of posterior segment structures through multifocal silicone IOLs was sufficient for retinal surface maneuvers during vitrectomy procedures in both fluid-filled and air-filled rabbit eyes.

Initial Clinical Experience With an Erbium:YAG Laser for Vitreoretinal Surgery

We tested the efficacy of an erbium:YAG laser for maneuvers in patients undergoing vitreoretinal surgery. An erbium:YAG laser equipped with a flexible fiberoptic and interchangeable 20-gauge endoprobes of various tip configurations ranging from 100 to 365 microns was used for specific maneuvers in 13 patients referred for vitreoretinal surgery for diabetic traction detachment, proliferative vitreoretinopathy, retinal detachment with posterior break, and epimacular membrane. The following maneuvers were performed: (1) transection of elevated vitreous membranes, (2) incision of epiretinal membranes, (3) drainage and relaxing retinotomy, (4) transection of subretinal membranes, (5) noncontact ablation of epiretinal membranes in air-filled eyes, (6) ablation of lens remnants, (7) posterior capsulotomy, (8) iris surgery, and (9) retinal vascular coagulation. Forty-eight defined maneuvers were performed with energy levels ranging from 0.2 to 5.0 mJ and repetition rates of 2 to 30 Hz. Transection of elevated membranes, subretinal membranes, and retinotomies were easily performed. Fourteen incisions into vascularized epiretinal membranes in diabetic traction detachment surgery demonstrated a fine margin of coagulation that permitted hemostatic incision. Retinal breaks were created during one of these incisions. Lens remnant ablation, posterior capsulotomy, and iris tissue removal were successful, with a single complication consisting of damage to the posterior surface of an intraocular lens during a pars plana posterior capsulotomy accomplished by means of a side-firing probe. Epiretinal membrane ablations in air-filled eyes were effectively performed in a gradual fashion without hemorrhage. The erbium:YAG laser offers precise and effective tissue cutting and removal in vitreoretinal maneuvers. Further study will determine the role of this technology in vitreoretinal surgery.

Management of the Dislocated Crystalline Lens with a Perfluorocarbon Liquid

AbstractVitreoretinal surgery allows the effective removal of soft to moderately dense crystalline lens fragments, using the vitrectomy probe and the ultrasonic fragmentation probe. Hard lenses cannot be removed with these instruments. Previously described techniques for removal of hard lenses include trapping the lens anteriorly with needles, cryoextraction of the lens in an air-filled eye, and manipulation with sodium hyaluronate. These methods are difficult and dangerous in some cases. We used perfluorocarbon liquid to facilitate the safe removal of a surgically luxated hard crystalline lens. Injection of the perfluorocarbon liquid floated the lens off the retinal surface and into the anterior vitreous cavity. In this location, the lens was delivered by using standard extracapsular cataract extraction techniques. This technique allowed removal of the hard crystalline lens with minimal manipulation, and was helpful in the setting of poor media clarity.

Experimental Transvitreal Cyanoacrylate Retinopexy Through Silicone Oil

We evaluated the use of transvitreal cyanoacrylate retinopexy in the treatment of experimental rhegmatogenous retinal detachment during vitreous surgery in rabbit eyes filled with silicone oil. The view to the fundus was superior to that obtained in our previous model of cyanoacrylate retinopexy in the air-filled eye. Glue delivery was consequently both easier and more precise through silicone oil relative to air. The chorioretinal adhesions produced with cyanoacrylate tissue adhesive were compared with those produced by transscleral retinal cryopexy and were found to be more rapid in onset as well as stronger. An exaggerated tissue response adjacent to the cyanoacrylate site suggested a potential toxic chemical or thermal reaction, or both, to the tissue adhesive, but there was no evidence of any distant ocular effects.

Intraocular Argon Laser Photocoagulation in the Management of Severe Proliferative Vitreoretinopathy

We surgically repaired seven eyes with severe proliferative vitreoretinopathy with intraocular argon laser photocoagulation. Five of the seven retinas were still attached six or more months postoperatively. Endolaser photocoagulation was used in conjunction with pars plana vitrectomy, periretinal membrane stripping, fluid-air exchange, and planned retinotomies. The advantages of endolaser photocoagulation include easier management of posterior retinotomies in an air-filled eye, isolation of anterior traction and retinal breaks by creating an encircling demarcation line posterior to the problem, and less manipulation of existing scleral buckling material.