Transscleral cyclophotocoagulation using a neodymium YAG laser

The effects of a neodymium: YAG laser, working in the free-running mode (1 and 20 millisecond pulses), upon the ciliary body via the transscleral route have been studied using 16 autopsy eyes. The experiments described were designed to find an efficient strategy of transscleral cyclodestruction of the ciliary body. It was found that pulse energies of between 6 and 7 Joules, an exposure duration of 20 milliseconds, and maximal defocusing are optimal. A beam, tangentially oriented and positioned 1/2 to 1 mm posterior to the limbus has a high probability of hitting the ciliary body and damaging the ciliary processes. In these experiments a first generation of contact lenses could not be demonstrated to have an advantageous effect.     

Intraocular pressure after peripheral retinal cryopexy in normotensive human eyes

Intraocular pressure (IOP) was measured before and after peripheral retinal cryopexy given for lattice degeneration and small retinal breaks. During the period of observation the IOP of treated eyes decreased, suggesting that freezing of areas remote from the ciliary body may lower IOP through mediation and/or transscleral outflow.     

Reattachment of the detached ciliary body with suturing for treatment of contusional ocular hypotension

Ocular hypotension resulting from a detached ciliary body after ocular contusion usually is best treated surgically. We report a simple, safe, and relatively effective procedure used to suture the ciliary body onto the inner surface of the sclera in eight such cases. Intraocular pressure (IOP) rose from unmeasurable levels to 10 to 12 mm Hg in five of these cases. Although in the three other cases IOP did not increase immediately after the operation, in one case it rose to 10 to 12 mm Hg 1 month postoperatively, and in the other two cases it rose to a normal level after additional laser therapy.     

Telerobotic contact transscleral cyclophotocoagulation of the ciliary body with the diode laser

To assess the feasibility of using the Robotic Slave Micromanipulator Unit (RSMU) to remotely photocoagulate the ciliary body for the treatment of glaucoma with the diode laser. In fresh unoperated enucleated human eyes, the ciliary body was destroyed either with a standard contact transscleral cyclophotocoagulation ‘by hand’ diode laser technique, or remotely using the RSMU. The treated sections were fixed in formalin, paraffin-embedded, and stained with hematoxylin and eosin. Histological evaluation was performed by a masked observer using a standardized grading system based on the amount of damage to the ciliary body to evaluate effectiveness of treatment. Both methods of contact transscleral cyclophotocoagulation showed therapeutic tissue disruption of the ciliary processes and both the non-pigmented and pigmented ciliary epithelium. Histology examination of remote robotic contact transscleral cyclophotocoagulation and “by hand” technique produced similar degrees of ciliary body tissue disruption. Remote diode laser contact transscleral cyclophotocoagulation of the ciliary body in fresh enucleated human eyes is possible with the RSMU. Therapeutic tissue disruption of the ciliary body was achieved. Additional study is necessary to determine the safety and efficacy of robotically-delivered cyclophotocoagulation in live eyes.     

Transscleral cyclophotocoagulation using a semiconductor diode laser in cadaver eyes.

We studied the effectiveness of semiconductor diode laser transscleral cyclophotocoagulation in cadaver eyes using the Miyake technique and light microscopy. Thermal lesions in the ciliary processes were induced with 0.7-second, 1200-mW, and 100- to 500-microns applications, 0.5 mm from the surgical limbus and defocused 1 mm posteriorly. An effective ciliary body reaction was observed grossly as tissue blanching, shrinkage, and pigment dispersion; and histologically, as coagulation necrosis and epithelial cell disruption. No damage to crystalline or intraocular lenses was evident. This successful application of diode laser transscleral cyclophotocoagulation in cadaver eyes suggests that it may prove useful in treating patients with glaucoma.     

Cyclocryotherapy in selected cases of congenital glaucoma

We investigated the efficacy of cyclocryotherapy, a procedure which destroys the ciliary epithelium, thereby decreasing the production of aqueous humor, by retrospectively studying 109 eyes with advanced primary congenital glaucoma that had undergone the procedure. The eyes were divided into two groups: group I comprised 75 eyes (69%) that had undergone conventional surgical procedures for congenital glaucoma prior to cyclocryotherapy; group II, 34 eyes (31%) that had not undergone any such previous procedures. All eyes were followed for at least 12 months after the last cyclocryotherapy. With "success" defined as "having an IOP greater than or equal to 8 mmHg, greater than or equal to 19 mmHg with or without medication," the success rate in all eyes was 30%, with no significant difference between the success rates in groups I and II (P greater than .05). Chronic hypotony (IOP less than 8 mmHg) was found in seven eyes (6%). Six eyes (6%) developed cataract during the course of treatment with cyclocryotherapy. Cyclocryotherapy appears to be a reasonable addition to the treatment of eyes with advanced, uncontrolled, primary congenital glaucoma.     

Photodynamic laser cyclodestruction with chloroaluminum sulfonated Phthalocyanine (CASPc) or photofrin®(PII) Vs. Nd:YAG laser cyclodestruction in a pigmented rabbit model

Background and Objective: To investigate Photofrin® (PII) and CASPc for photodynamic therapy (PDT) of the ciliary body in rabbits. Study Design/Materials and Methods: PII (10 mg/kg) or CASPc (1 mg/kg) was given by ear vein. Pharmacokinetics were studied in frozen sections by fluorescence microscopy (CCD camera based low light detection system with digital image processing) at 1 and 24 h (8 rabbits;16 eyes). Laser light was delivered (argon pumped dye laser;630 and 675 nm;8 rabbits;16 eyes) by contact fiberoptic. To compensate for iris attenuation, irradiance was 125 mW/cm² (20, 40, 80, or 160 J/cm²). Controls (4 rabbits;8 eyes) received laser light without photochemicals (OD) and for comparison, continuous wave Nd:YAG laser by fiberoptic (0.8–1.2J;OS). Results: Localization studies showed intravascular distribution with some selective ciliary body distribution at 24 h (PII > CASPc). Rabbits treated with PII or CASPc exhibited variable amounts of gross ciliary body edema, infarction, and necrosis by 24–48 h. This response was not seen in PDT control tissues;damage was seen in the iris and ciliary body, with partial vacuolization of the pigment epithelium. Conclusion: PDT may offer a more selective approach to ciliary body destruction. A small but significant thermal effect was seen during PDT from melanin photon uptake with damage to iris and ciliary body. Thermal damage and potential interaction with ocular visual pigments may limit use of these photochemicals and wavelengths for PDT of the ciliary body © 1995 Wiley-Liss, Inc.     

Subconjunctival THC: YAG laser limbal sclerostomy Ab externo in the rabbit

A chromium-sensitized, and thulium and holmium-doped YAG laser (THC:YAG laser) was used to create bilateral limbal sclerostomies in six Dutch pigmented rabbits. The laser is a long-pulsed (300 microseconds) [corrected], compact, self-contained, solid-state laser operating in the near infrared (2.1 microns). A 1-mm conjunctival stab incision was made 12 mm away from the sclerostomy site to allow entry of a specially designed 26-gauge (480 microns) optic probe that delivers energy at right angles to the long axis of the fiber. Probe insertion minimally disturbed the conjunctiva. Pulse energies of 60 to 150 mJ were used with a repetition rate of 5 pulses/s. Energy levels ranging from 1.35 to 6.6 J produced full-thickness sclerostomies. Histopathology showed a sharply defined perforating limbal wound at all energy levels. The overlying conjunctiva was intact, with swelling of the adjacent cornea. A peripheral iridectomy was intentionally created with the laser through the peripheral limbus, resulting in a sharply defined perforating tract through the iris/ciliary body. This technique may simplify filtering sclerostomy surgery, without anterior chamber instrumentation and with minimal conjunctival trauma.     

A new endoscope for ophthalmic microsurgery.

We present an endoscope designed for ophthalmic microsurgery. The handpiece contains a charge-coupled device, a solid-state imager (250,000 pixels), and a probe (either 0.89 or 1.5 mm in diameter), including the light guide. The light source is a halogen lamp. The clear views the instrument provides of the ciliary sulcus and ciliary body behind the iris make it useful in secondary posterior chamber intraocular lens implantation using the ciliary sulcus suturing technique, and in endolaser photocoagulation of the ciliary body in end-stage glaucoma. It also is useful in performing vitrectomy in cases in which visualization is difficult because of corneal opacification or fluid-gas exchange.     

Neodymium: YAG laser transscleral cyclophotocoagulation for glaucoma after penetrating keratoplasty

Nd:YAG laser cyclophotocoagulation (CPC) of the ciliary body is a promising cyclodestructive treatment for the management of refractory glaucoma following penetrating keratoplasty. Twenty-eight eyes (27 patients) were treated between August 1985 and September 1987 and followed 6 to 24 months (median, 18 months). The mean intraocular pressure (IOP) was initially 39 mm Hg (range, 30 to 70 mm Hg) on maximally tolerated medications. The Lasag Microrupter 2 was used in the free-running thermal mode with a mean pulse energy of 4.13 J. The laser was retrofocused 3.6 mm from the conjunctival surface and 30 to 50 applications per treatment (mean, 37.5) were given 2 to 3 mm from the limbus for 360 degrees (71%) or 180 degrees (29%). Multiple treatments were necessary in 13 eyes (46%). After CPC, IOP fell to 22 mm Hg or below in 18 eyes (64%) at 3 months, in 20 of 27 eyes (74%) at 6 months, and in 16 to 24 eyes (67%) at 1 year. Inadequate IOP control in four of 28 eyes necessitated cyclocryotherapy in three patients and a Schocket procedure in one other. Of the 14 clear pre-CPC grafts six (43%) became edematous during follow-up. All of the failed grafts had undergone multiple CPCs.     

Safety of high-energy neodymium:YAG laser pulses in YAG sclerostomy

YAG sclerostomy was performed in 15 eyes of nine cynomolgus monkeys. Individual pulse energies ranged between 10 and 135 millijoules. Total pulse energy ranged between 2,000 and 36,000 millijoules in order to test the extreme range of energy that might be required. Both acute effects and chronic effects were studied in the corneal endothelium, the lens capsule, the iris, the ciliary body, the retina, and the sclera. Techniques included flat preparations of the corneal endothelium, paraffin sections for light microscopy, and scanning and transmission electron microscopy. Our conclusion is that individual pulse energies of up to 135 millijoules with a total of up to 36 joules of energy are safe in monkey eyes when performing YAG sclerostomy.     

Intraocular pressure variation during colorectal laparoscopic surgery: standard pneumoperitoneum leads to reversible elevation in intraocular pressure

Background

The potential effects of laparoscopic surgery on intra- and postoperative intraocular pressure (IOP) are not completely understood. Although prior studies have reported that pneumoperitoneum may increase IOP, it is not clear whether this increase is related to the effects of pneumoperitoneum or to the patient’s position, such as the Trendelenburg position. This study aimed to evaluate the potential fluctuations of IOP during colorectal laparoscopic surgery in two groups of patients: those with and those without Trendelenburg positioning.

Methods

For this prospective study 45- to 85-year-old patients undergoing laparoscopic colorectal surgery were enrolled after a thorough ophthalmologic assessment. The study protocol included measurement of IOP at eight different time points (before, during, and after surgery) using a contact tonometer in both eyes.

Results

The study enrolled 29 patients: 17 (58.6 %) with Trendelenburg position placement during surgery and 12 (41.4 %) without Trendelenburg positioning. The two groups did not differ in terms of gender, age, body mass index (BMI), American Society of Anesthesiology (ASA) class, or operative time. In all the patients, pneumoperitoneum induction led to a mild rise in IOP, averaging 4.1 mmHg. The patients with Trendelenburg positioning showed a greater increase than the patients without it (5.05 vs 4.23 mmHg at 45 min; p = 0.179), but IOP evaluation 48 h after surgery showed no substantial differences between the two groups. Among the 29 patients, 17 (58.6 %) showed an increase in IOP of 5 mmHg or more during surgery. A greater percentage of the patients who underwent Trendelenburg positioning showed an IOP increase of 5 mmHg or more (76.5 vs 33.3 %; p = 0.020). At the multivariate analysis, no potential predictors of increased IOP during surgery was identified.

Conclusions

Standard pneumoperitoneum (≤14 mmHg) led to mild and reversible IOP increases. A trend was observed toward a greater IOP increase in patients with Trendelenburg positioning. Thus, the patient’s position during surgery may represent a stronger risk factor for IOP increase than pneumoperitoneum-related intraabdominal pressure.     

Trans-scleral application of a semiconductor diode laser

We used a diode laser with an output power of 1 W through a fiberoptic light pipe (200 microns diameter) to deliver laser energy through the sclera of pigmented rabbits. Ciliary body destruction occurred with energy levels of 300-400 mW and exposure time of 0.5 sec. Retinal photocoagulation was achieved with energy levels of 200-500 mW in 0.5 sec. Histologic examination of acute lesions demonstrated thermal destruction of ciliary body processes and retina. Chorioretinal scar formation was observed clinically and histologically within 2-3 weeks. Our data indicate that the transscleral diode laser may be used for destruction of the ciliary body processes or peripheral retinal coagulation in pigmented eyes.     

The effects of atropine and glycopyrrolate on intra-ocular pressure in anasthetised elderly patients

The effects of glycopyrrolate 0.2 mg and atropine 0.6 mg, given intravenously, were studied in 40 elderly patients undergoing intra-ocular surgery. Twenty patients had normal intra-ocular pressure (IOP) and 20 had raised IOP. The effects of each of the drugs on IOP, heart rate, prevention of the oculocardiac reflex and incidence of dysrhythmias were assessed. Anaesthesia with thiopentone, suxamethonium, nitrous oxide/oxygen, and halothane, using a semiclosed circle system resulted in a decrease in mean IOP in both the atropine and glycopyrrolate groups. Patients who had pre-existing raised IOP showed a significantly greater decrease in IOP than those with normal IOP. Patients with raised IOP who had received atropine experienced a greater decrease in IOP than those who had received glycopyrrolate. Both atropine and glycopyrrolate were effective in preventing the oculocardiac reflex. The increase in heart rate was greater in those patients who had received atropine. The incidence of dysrhythmias was low.     

Effect of Hemodialysis on Intraocular Pressure

Abstract: Intraocular pressure (IOP) was determined in 13 dialysis patients before, during, and after dialysis. The values were compared with those obtained in an age-, sex-, and time-matched normal control group. The IOP values obtained in dialysis patients were significantly lower than those in the control group. An insignificant decrease in IOP was noted during the first 2 h of dialysis. This was followed by a slight rise above the base line by the end of dialysis. Although the middialysis IOP was significantly lower than the postdialysis value, the latter was not significantly different from the predialysis value. Our results are at variance with several earlier studies demonstrating marked increase in IOP during dialysis. Lack of significant rise in IOP during dialysis in our study seems to be due to improved dialytic technique and better uremia control employed here as compared with the earlier studies.     

The effect of indocyanine green pretreatment on the parameters of transscleral diode laser thermotherapy-induced threshold coagulation of the ciliary body

BACKGROUND AND OBJECTIVE: To study the effect of indocyanine green (ICG) pretreatment on threshold parameters of transscleral diode laser thermotherapy-induced threshold coagulation of the ciliary body. The procedure was termed 'cyclothermotherapy' based on the long duration (15-60 seconds) of diode laser application. STUDY DESIGN/MATERIALS AND METHODS: The right eyes of nine young adult New Zealand white rabbits underwent transscleral cyclothermotherapy (TCT, Group 1), TCT following ICG pretreatment (Group 2), and external manipulation of the ciliary body alone (Group 3). Rabbits were sacrificed after 24 hours; specimens were evaluated with gross examination and light microscopy. RESULTS: Thresholds were 30 J/cm2 (TCT) and 4.5 J/cm2 (TCT with ICG). Widespread structural damage was seen in the ciliary processes and the ciliary body in Groups 1 and 2. In Group 3, external manipulation of the ciliary body caused hemorrhage and structural damage confined to the ciliary processes. CONCLUSION: ICG pretreatment reduced the energy necessary to cause a threshold lesion with TCT in nonpigmented rabbits.     

Intraocular pressure in uremic patients on chronic hemodialysis

Intraocular pressure (IOP) was measured before and after hemodialysis in 30 uremic patients receiving regular treatment. Osmolality, blood pressure and weight before and after dialysis were also determined. Low IOP of 11.4 +/- 2.7 and 11.5 +/- 3.1 mm Hg was found in the left and right eye, respectively. Following hemodialysis osmolality, blood pressure and body weight decreased significantly but IOP did not rise significantly. This study suggests that there is only a remote possibility for severe IOP increase following hemodialysis in uremic patients on chronic treatment.     

The long-term effect on intraocular pressure of a procedure combining trabeculectomy and cataract surgery, as compared with trabeculectomy alone

The long-term reduction of intraocular pressure (IOP) resulting from a procedure combining extracapsular cataract extraction and posterior chamber lens implantation with trabeculectomy was compared retrospectively with the IOP-lowering effect of trabeculectomy alone. Forty patients who underwent the combined procedure and 38 who underwent trabeculectomy alone had been followed for an average of 22 +/- 7 months. Both these surgical procedures significantly reduced IOP, but after a year or more, pressure levels were significantly lower in the trabeculectomy group than they were in the combined group: 12.8 +/- 4.2 mm Hg, and 16.5 +/- 5.6 mm Hg, respectively, at 18 months. Also, the mean postoperative fall in IOP was greater in the "filtered" eyes than it was in the combined group (9.8 +/- 4.6 mm Hg and 12.1 +/- 5.2 mm Hg, respectively, at 18 months). Finally, the number of medications required to maintain controlled IOP in the combined group was greater (and resumed preoperative values at 2 years) than it was in the trabeculectomy group (62.5% of the filtered eyes remained controlled unaided).     

Partial ciliary process laser photocoagulation in the management of glaucoma

Partial ciliary processes argon laser photocoagulation (PCLP) in the management of glaucoma has been the subject of a carefully conducted, prospective 5+-year clinical trial in 22 eyes of 20 patients. The mean intraocular pressure (IOP) ± SD was significantly lower (15.5 ± 3.6 mm Hg) than before the procedure (29.9 ± 10.1 mm Hg; 0.001 < P < 0.005, paired t-test). The mechanism of intraocular pressure reduction is due mainly to the reduction in the rate of aqueous humor formation with a mean outflow facility (C-value) ± SD of 0.12 ± 0.11 before and 0.1 2 ± 0.06 μl/min/mm Hg after the procedure. This new procedure, done on an out-patient basis, shows promise as a convenient, low-risk, and useful alternative procedure in selected glaucoma cases that are poorly controlled by medical or surgical measures. This new approach may also be used as an adjunct in the medical and/or surgical management of aphakic and ciliary block glaucoma.     

Surgical approach to lamellar sclerouvectomy for posterior uveal melanomas: the 1986 Schoenberg lecture

We describe a technique of surgically removing melanomas that involve the ciliary body and/or the choroid, while leaving intact the outer portion of the sclera and the overlying sensory retina. This procedure, called a partial lamellar sclerouvectomy, can be subclassified as a partial lamellar sclerocyclochoroidectomy in the case of ciliochoroidal melanomas, and as a partial lamellar sclerochoroidectomy in the case of pure choroidal melanomas.