Sylvain Roy

New TonoPen XL : comparison with the Goldmann tonometer

Purpose To compare the intraocular pressure (IOP) values obtained using a Goldmann tonometer (Haag-Streit) with those obtained with the new Tonopen XL (Mentor), which has certain differences compared with first- and second-generation models.Methods The IOPs of 104 patients were assessed by Goldmann tonometer and Tonopen XL tonometer. Goldmann measurements was done first in 145 eyes and Tonopen measurements were done first in 53 eyes. Four observers measured the IOP. Observers A, B and C used the Goldmann tonometer first and then the Tonopen XL, while observer D used the Tonopen XL first and then the Goldmann tonometer. The results were analysed by descriptive analysis and, when the distribution of the data was normal, paired t-test and Pearsons r coefficient were used to compare and correlate IOP measurements between Goldmann and Tonopen measurements. When the distribution of the data was non-normal, the Wilcoxon matched-pair test and Spearman coefficient were used. The agreement between Goldmann and Tonopen values was also calculated. ANOVA test was used to compare the difference obtained by ‘Goldmann minus Tonopen’ measurements among the three different observers.Results A statistically significant difference (p > 0.0001) was found between the IOP readings obtained by Goldmann tonometer and the Tonopen XL and a significant correlation was found between the Goldmann values and Tonopen XL values (p > 0.001). When the Goldmann IOP was more than 20 mmHg the Tonopen XL measurements were lower than the Goldmann values. Also in this group this difference was statistically significant. No significant difference was found between Goldmann values and Tonopen values among the three observers, even though a significant difference was found between Goldmann values and Tonopen values for observer B. When the values obtained by first the Goldmann tonometer and then the Tonopen XL were compared with those obtained by first the Tonopen XL and then the Goldmann tonometer, no significant difference was found between the two groups.Conclusion The new Tonopen XL provides similar results to the Goldmann tomometeri 62% of the cases and was slightly less accurat than the Goldmann tonometer for extreme values, just like the previous Tonopen. Nevertheless the precision is good enough for the purpose of adequate screening.

Ten years follow-up after deep sclerectomy with collagen implant.

PurposeTo evaluate the long-term success rate and complications of nonpenetrating deep sclerectomy with collagen implant in open-angle glaucoma. Patients and MethodsClinical, prospective, monocentric, nonrandomized, unmasked study on 105 patients with medically uncontrolled glaucoma. A standard procedure deep sclerectomy with collagen implant was performed. Complete examinations were performed before surgery and postoperatively at 1 and 7 days; 1, 2, 3, 6, 9, and 12 months and then every 6 months during the 10 following years. ResultsThe mean follow-up was 101.5±43.1 (3 to 144) months [mean±SD, (range)]. The preoperative intraocular pressure (IOP) was 26.8±7.7 (14 to 52) mm Hg and the best-corrected visual acuity 0.71±0.33 (0.02 to 1.5). Ten years after surgery IOP was 12.2±4.7 (6 to 20) mm Hg and best-corrected visual acuity 0.63±0.34 (0.01 to 1.2) (number of remaining patients=52). The mean number of medications per patient went from 2.3±0.7 (1 to 4) down to 1.3±1.1 (0 to 3). An IOP ≤21 mm Hg without medication was achieved in 47.7% patients and in 89% with or without treatment. One major complication was reported. Goniopuncture was performed in 61 eyes (59.8%), 5-fluorouracil treatment given to 25 patients postoperatively and included needling (n=5). ConclusionsOn the basis of a 10-year follow-up deep sclerectomy with collagen implant demonstrated its efficacy in controlling IOP with few postoperative complications.

Descemet membrane detachment after nonpenetrating filtering surgery.

PurposeTo make surgeons performing nonpenetrating filtering surgery aware of an unusual complication namely Descemet membrane detachment. MethodsWe retrospectively reviewed nine eyes of nine patients seen in our hospital with Descemet membrane detachment occurring after nonpenetrating filtering surgery from January 1994 to December 2000. ResultsBoth planar and nonplanar detachments were reported. Neither scrolls nor tears in the Descemet membrane were observed in any patient.After viscocanalostomy (four patients), the detachment was generally noticed shortly after the procedure and the cornea maintained its clarity. After deep sclerectomy with a collagen implant (five patients), it developed weeks to months postoperatively with adjacent corneal edema.Four patients had descemetopexy. None required more than one procedure. However, at the last visit, two detachments persisted although they had diminished in size: one after viscocanalostomy and conservative treatment and one after descemetopexy after deep sclerectomy with a collagen implant.To date otherwise, no signs of significant corneal damage could be observed clinically nor by specular microscopy and pachymetry. ConclusionsThe diagnosis of Descemet membrane detachment can be easily overlooked or misdiagnosed. The clinical presentation, clinical course, and pathogenesis depend on the type of nonpenetrating filtering surgery performed. Ophthalmologists should be aware of this unusual complication, which is likely to be more common after nonpenetrating filtering surgery than after trabeculectomy. A period of observation before attempting descemetopexy is recommended.

3D simulation of the aqueous flow in the human eye

Glaucoma results in an increase in the resistance of the aqueous humor outflow, which in turn leads to an increase of the intraocular pressure (IOP). Several treatments are proposed to reduce and stabilize the IOP that include medications, filtering surgery and glaucoma drainage devices (GDD). So far computational fluid dynamics (CFD) modeling of the eye drainage system has not yet been well studied. Therefore our goal was to provide a 3D CFD model of the eye based on the anatomy of a real human eye. Such a tool would serve for future evaluation of new glaucoma surgical techniques involving, for example, GDD. The model was based on stacks of microphotographs from human eye slides from which digital processing of the images of the eye structure and 3D reconstruction of the model were performed. Simulations of the distribution of pressure and flow velocity in the model of a healthy eye gave results comparable to physiology references. Mimicking glaucoma conditions led to an increase of the IOP from normal range, which went down to lower values after a filtering procedure. Further refinements in the boundary conditions for the filtering procedure shall improve the accuracy of this innovative tool for modeling glaucoma surgery.

Crosslinked Sodium Hyaluronate Implant in Deep Sclerectomy for the Surgical Treatment of Glaucoma

Purpose To evaluate the efficacy and safety profile of a new crosslinked sodium hyaluronate drainage implant in nonpenetrating glaucoma surgery. Methods From July 2008 until January 2010, 55 eyes from 55 patients with glaucoma were operated upon. After a standard deep sclerectomy was performed, a crosslinked sodium hyaluronate (HEALAflow®) was injected under the superficial scleral flap and underneath the conjunctiva. The main outcomes measured were mean intraocular pressure (IOP), mean number of antiglaucoma medications, presence of postoperative complications, and clinical aspect of the filtering bleb. Results For the 55 eyes, the mean follow-up was 12.0±5.1 months, the mean preoperative IOP was 21.6±7.2 mmHg, and the mean number of antiglaucoma medications before surgery was 2.4±1.2. At final follow-up visits, the mean IOP went down to 11.5±3.0 mmHg; the mean number of antiglaucoma medications was reduced to 0.5±0.9. The filtering bleb was visible on 49 eyes (89%). There were 5 hypotonies (IOP < 6 mmHg) and 3 iris incarcerations. Complete success rate (IOP ≤18 mmHg without antiglaucoma medication) was 70% and the overall success rate (IOP ≤18 mmHg with and without antiglaucoma medication) was 91%. Conclusions The slow resorbable highly crosslinked sodium hyaluronate drainage implant fills up the intrascleral and subconjunctival space, preventing postoperative scarring and fibrosis of the filtering site and helping to maintain a functional filtration after nonpenetrating glaucoma surgery. The IOP was significantly lowered with few numbers of postoperative complications and less medication.

Arterial biomechanics after destruction of cytoskeleton by Cytochalasin D.

Vascular smooth muscle is a major structural element of the arterial wall. We examined the effects of cytoskeleton destruction, after administration of Cytochalasin D, on the biomechanical properties of porcine common carotids. Compared to untreated, maximally dilated controls, Cytochalasin D-treated arteries have shown a marked increase in compliance in the elastin-dominated pressure range. After weakening the VSM stress-bearing cytoskeleton by Cytochalasin D the artery would expand, reaching a new equilibrium state. This study brings further evidence that VSM is under tension, even when it is under zero load and at maximal vasodilation. This residual tension was released upon partial destruction of the cytoskeleton with Cytochalasin D. From a biomechanical standpoint, this means that the zero stress states of the in-series and parallel elastic components are substantially different.

A new adjustable glaucoma drainage device.

PURPOSE This work is focused on the testing of a new experimental noninvasively adjustable glaucoma drainage device (AGDD) that allows for the control of its outflow resistance to modulate intraocular pressure (IOP) in a customized fashion. METHODS Six AGDDs were directly connected to a pressure transducer and a perfusion system continuously delivering saline solution at rate of 2 μL/min. The steady-state pressure was measured and reported as a function of the angular position of the AGDD disk. Ex vivo experiments were conducted on six freshly enucleated rabbit eyes. The IOP was measured, and the flow rate was increased with a syringe pump to simulate elevated IOP associated with glaucoma. After insertion of the implant in the anterior chamber, the position of the disk was sequentially adjusted. RESULTS The relation between the pressure drop and the angular position of the AGDD disk is nonlinear. The functional range lies between 80° and 130°, which allows for four or five different reproducible adjustment positions. Above 130° the implant is considered to be closed (no outflow), and below 80° it is considered to be open (minimum resistance to flow). CONCLUSIONS The resistance to outflow of the experimental AGDD can be adjusted to keep IOP in the desired physiological range. This feature could be useful for addressing the risk of hypotony in the early postoperative stages and could provide a means to achieve optimal IOP under a wide range of postoperative conditions.

Results of CO2 Laser-assisted Deep Sclerectomy as Compared With Conventional Deep Sclerectomy

Purpose:To evaluate the efficacy of CO2 laser-assisted sclerectomy surgery (CLASS) compared with classic nonpenetrating deep sclerectomy (NPDS) with implant in medically uncontrolled glaucoma patients. Materials and Methods:Patients who underwent primary filtration surgery with CO2 laser system at the time interval between July 2010 and April 2011 were identified, their medical files were reviewed, and their results were compared with matched control group who underwent classic NPDS with intrascleral implant at the same time period. Intraocular pressure (IOP) was measured at baseline, 1 week, and 3, 6, 12, 18, and 24 months, respectively. Main outcome measures were: IOP, use of supplemental medical therapy, and failure (5 mm Hg>IOP>18 mm Hg, reoperation for glaucoma, or loss of light perception). Results:A total of 58 patients were reviewed, including 27 in the CLASS group and 31 in the NPDS group. For the CLASS group the follow-up (mean±SD) was 20.7±6.8 months, the mean preoperative IOP was 23.3±8.2 mm Hg (range, 10 to 38 mm Hg), and the mean number of antiglaucoma medication before surgery was 3.0±1.0 (range, 1 to 4). At final follow-up visits, the mean IOP was 11.7±3.1 mm Hg (range, 6 to 19 mm Hg), and the mean number of antiglaucoma medication was reduced to 1.0±1.6 (P<0.0003). The complete success rate (IOP⩽18 mm Hg without antiglaucoma medication) was 73% and the qualified success rate (IOP⩽18 mm Hg with/without antiglaucoma medication) was 96%. For the control group the mean follow-up was 17.6±6.7 months, the mean preoperative IOP was 23.1±7.3 mm Hg (range, 14 to 44 mm Hg), and the mean number of antiglaucoma medication before surgery was 3.0±0.8 (range, 1 to 4). At final follow-up visits, the IOP was 13.3±3.6 mm Hg (range, 8 to 20 mm Hg), and the mean number of antiglaucoma medication was reduced to 0.7±1.1 (P<0.0004). The complete success rate and the qualified success rate were 71% and 89%, respectively. Conclusions:A new technique using a CO2-laser ablation system allows precise and easy creation of the scleral space and ablation of Schlemm canal. This technique has been shown to be as efficient as the standard NPDS surgery in terms of IOP-lowering effect. This would render the deep sclerectomy an easier glaucoma surgery.

In Vivo Testing of a Novel Adjustable Glaucoma Drainage Device

PURPOSE We report on the in vivo testing of a novel noninvasively adjustable glaucoma drainage device (AGDD), which features an adjustable outflow resistance, and assess the safety and efficiency of this implant. METHODS Under general anesthesia, the AGDD was implanted on seven white New Zealand rabbits for a duration of 4 months under a scleral flap in a way analogous to the Ex-PRESS device and set in an operationally closed position. The IOP was measured on a regular basis on the operated and control eyes using a rebound tonometer. Once a month the AGDD was adjusted noninvasively from its fully closed to its fully open position and the resulting pressure drop was measured. The contralateral eye was not operated and served as control. After euthanization, the eyes were collected for histology evaluation. RESULTS The mean preoperative IOP was 11.1 ± 2.4 mm Hg. The IOP was significantly lower for the operated eye (6.8 ± 2 mm Hg) compared to the nonoperated eye (13.1 ± 1.6 mm Hg) during the first 8 days after surgery. When opening the AGDD from its fully closed to fully open position, the IOP dropped significantly from 11.2 ± 2.9 to 4.8 ± 0.9 mm Hg (P < 0.05). CONCLUSIONS Implanting the AGDD is a safe and uncomplicated surgical procedure. The fluidic resistance was noninvasively adjustable during the postoperative period with the AGDD between its fully closed and fully open positions.

Eyewatch, an Innovative Adjustable GDD for the Treatment of Glaucoma – in Vivo Results

PURPOSE: To report the in vivo results of a continuously adjustable glaucoma drainage device (GDD) in glaucoma surgery with rabbits.