Biomedical subjects

A Mermoud

Publications and source records attributed to A Mermoud.

At least 73 records · Page 4Linked to original sources

PubMed1997

[Cataract-glaucoma combined surgery: comparison between phacoemulsification combined with deep sclerectomy, or trabeculectomy].

PURPOSE: To study the success rate of combined phaco-intraocular lens (IOL)-deep sclerectomy (P-DS), a new perforating filtering surgery, versus phaco-IOL-trabeculectomy (P-T). METHODS: Of 38 patients, 39 eyes with cataract and different types of glaucoma, 19 eyes underwent P-DS, and 20 eyes underwent P-T. Patients were prospectively studied. RESULTS: The follow-up of both groups was 11 +/- 6 months. The intraocular pressure (IOP) decrease in both groups was similar (from a mean preoperative IOP of 26.5 +/- 6.8 mmHg, to a mean postoperative IOP of 14.8 +/- 1.3 mmHg in the P-DS group, vs 25.9 +/- 7.7 mmHg preoperative and 14.8 +/- 2.7 mmHg postoperative in the P-T group). The visual acuity outcome was similar in both groups. The complication rate was significantly lower in the P-DS group. CONCLUSIONS: Deep sclerectomy associated with cataract surgery offers the same IOP reduction and visual acuity outcome. However, the complication rate is significantly lower and allows easier ambulatory care.

Aged↗

PubMed1997

[Comparative results of deep sclerectomy transformed to trabeculectomy and classical trabeculectomy].

OBJECTIVE: To study the learning risk of a new surgical technique, the deep sclerectomy (DS), which may be complicated with a perforation of the trabeculodescemetic membrane. To do so, we compared the results and the complications of patients who underwent DS transformed in trabeculectomy (DSt) and those of patients who underwent trabeculectomy (TE). MATERIALS AND METHODS: Between june 1994 and june 1996, we performed 234 DS, 19 of them had to be transformed into a TE, because of a perforation of the trabeculodescemetic membrane during the deep sclerocorneal dissection. Two matched groups of patients were prospectively followed, one group including 19 DSt and a control group including 19 TE. RESULTS: The IOP decrease on the first postoperative day was greater in the DSt-group compared to the TE-group (2.32 +/- 3.89 vs 6.73 +/- 4.31, p = 0.004). Scleral perforations occurred mainly during the learning phase of this new surgical technique. Postoperative complications were similar in both groups, except for hypotony and hyphema which were more frequent in the DSt-group (hypotony: 90% vs 37%, p = 0.0019; hyphema: 68% vs 16%, p = 0.017). The long term success rate with or without medication were comparable in both groups. CONCLUSION: This study shows that, when a DS is complicated with a perforation of the trabeculodescemetic membrane, the long term success rate of the surgery is similar to that of trabeculectomy. However, immediate postoperative complications such as hypotony and hyphema are increased. These results should encourage surgeons to learn this new non perforating filtration surgery.

Aged↗

PubMed1997

[Physiopathology of uveitic glaucoma].

Chronic secondary glaucoma is a common and serious complication of uveitis, even if intraocular pressure (IOP) is low during episodes of ocular inflammation. Management of the glaucoma is difficult because of the often chronic course of the underlying disease, and blindness is a common consequence. Several pathophysiologic mechanisms may be involved in the development of uveitic glaucoma. The glaucoma can be acute or chronic, and associated with open or closed anterior chamber angle. Elevated IOP can be the result of active inflammation, corticosteroid therapy, insufficient glaucoma therapy, or permanent changes in ocular structures that alter aqueous humor dynamics. Because the etiologic factors and pathologic mechanisms involved in uveitic glaucoma are so complex, diagnostic and therapeutic decisions are guided by carefully delineating the pathophysiology of each individual case. The goal of treatment is to minimize permanent structural alterations of aqueous outflow and to prevent damage to the optic nerve. New aspects of uveitic glaucoma physiopathology are presented.

Chronic Disease↗

PubMed1997

Releasable suture technique for trabeculectomy.

A retrospective review of 154 trabeculectomies with releasable sutures was performed to assess the effect of suture release on intraocular pressure (IOP) at various postoperative periods. Release of the suture was necessary in 38% of cases. The immediate reduction in IOP was significant (p < 0.01) when the suture was released during the first three postoperative weeks. Seventy percent of eyes had a reduction in IOP more than 5 mmHg if released within the first week compared to 20% after the third week. With suture release after the third postoperative week, there was no clinically significant decrease in IOP. The decrease in IOP was similar in eyes undergoing trabeculectomy alone or when cataract extraction through a separate corneal incision was undertaken simultaneously. The period during which release of suture was effective was not prolonged by use of antimetabolites. Complications included a typical windshield-wiper keratopathy (18 eyes), failure to release the suture (13 eyes), epithelial abrasion (6 eyes) and a sub-conjunctival bleed (1 eye).

Cataract Extraction↗

PubMed1996

Aqueous humor dynamics in rats.

BACKGROUND: In order to determine normal outflow facility and aqueous humor production values in Lewis rats, we established methods of measuring aqueous humor dynamics in this animal. METHODS: Outflow facility was determined using anterior chamber infusion with constant pressure. Aqueous humor production was determined by a technique of dilution with FITC-albumin. RESULTS: The mean outflow facility was 0.044 +/- 0.01 microliter/min/mmHg. Rats weighing less than 300 g had lower values than did rats weighing more than 300 g (0.034 +/- 0.006 microliter/min/mmHg vs 0.050 +/- 0.015 microliter/min/mmHg, P = 0.009). The mean aqueous humor production was 0.350 +/- 0.110 microliter/min. The turnover rate of aqueous humor production per minute was 2.23%. CONCLUSIONS: Anterior chamber infusion with constant pressure and the FITC-albumin method allow measurement of the outflow facility and aqueous humor production in Lewis rats. These methods may be useful in assessing aqueous humor dynamics when rats are used as a glaucoma model.

Animals↗

PubMed1996

[Malignant ciliary block glaucoma after deep sclerotomy--ultrasound biomicroscopy imaging].

BACKGROUND: We present the case report of a patient who presented with malignant glaucoma following deep sclerectomy with collagen implant in both eyes. To assess the IOP spike mechanisms in ciliary bloc glaucoma, we performed ultrasound biomicroscopy before and after the second filtration surgery (right eye). MATERIALS AND METHODS: A 60-year-old hyperopic patient with bilateral medically uncontrolled open-angle glaucoma underwent deep sclerectomy with collagen implant in the left eye and one month later in the right eye. Both eyes presented postoperatively a ciliary bloc glaucoma. Ultrasound biomicroscopy was performed pre- and postoperatively during the malignant glaucoma crisis in the right eye. RESULTS: Preoperative ultrasound imaging showed an anterior rotation of the ciliary body. That disappeared with local application of cycloplegics. During the malignant glaucoma crisis, the ciliary body came again in touch with the lens, thus blocking the aqueous humor pathway to the anterior chamber. Malignant glaucoma occurred despite the nonperforation of the eye undergoing deep sclerectomy with collagen implant. CONCLUSIONS: In our patient, the anterior rotation of the ciliary body and its subsequent malignant glaucoma might be either a consequence of a ciliary muscle spasm due to postoperative inflammation or of acute IOP drop. Finally, in hyperopic eyes, the ciliary muscle may be hypertrophied due to constant accommodation.

Aqueous Humor↗

PubMed1996

[Uveal effusion syndrome: clinical and ultrastructural aspects].

UNLABELLED: Spontaneous serous detachment of the choroid and ciliary body, together with bullous serous detachment of the retina (uveal effusion syndrome) is a rare but well-defined syndrome frequently associated with nanophthalmos. CASE REPORTS: Based on three cases whose one familial, clinical and ultrastructural characteristics of the syndrome are reviewed and the role of ultrasonic biomicroscopy (UBM) presented. CONCLUSION: The severe and potentially blinding complications encountered after any surgery on these eyes make the recognition of the classical clinical signs and symptoms of the syndrome particularly important. In this context, UBM represents an interesting new tool in terms of diagnosis and pathophysiology understanding.

Ciliary Body↗

PubMed1996

Ultrasound biomicroscopy of eyes undergoing deep sclerectomy with collagen implant.

AIMS: To assess the intraocular pressure (IOP) lowering mechanism of deep sclerectomy with collagen implant (DSCI), a non-penetrating glaucoma surgery. METHODS: Nine eyes of nine patients with medically uncontrolled open angle glaucoma underwent DSCI. Ultrasound biomicroscopy (UBM) of the sclerectomy site was performed 1 month after surgery. The following factors were assessed: length and height of collagen implant, and thickness of the residual trabeculocorneal membrane. RESULTS: Postoperative IOP decreased significantly in all nine eyes from a preoperative mean value of 25.8 (SD 4.8) mm Hg to a postoperative (1 month) mean value of 11.3 (6.3) mm Hg (p = 0.001). In all nine eyes, UBM at 1 month after surgery showed a subconjunctival filtration through the thin trabeculocorneal membrane and through the scleral flap around the collagen implant. In four cases, a hypoechoic area in the suprachoroidal space was observed and might represent ciliary body detachment or be due to suprachoroidal drainage of aqueous humour through the thin deep scleral wall. At 1 month after surgery the mean trabeculocorneal membrane thickness was 110.1 (16.8) microns, and the mean length and height of the collagen implant were 2.3 (0.1) mm and 1.1 (0.1) mm respectively. CONCLUSION: DSCI lowered IOP by allowing aqueous filtration through a thin trabeculocorneal membrane to the subconjunctival space and, eventually, to the suprachoroidal space.

Aged↗

PubMed1996

Effects of intraoperative mitomycin-C on the function of Baerveldt glaucoma drainage implants in rabbits.

PURPOSE: The purpose of this study was to assess the effects of intraoperative mitomycin-C (MMC) on the function of Baerveldt glaucoma implants in rabbits. METHODS: Bilateral implantations of 200 mm2 Baerveldt drainage devices were performed in 30 normal albino rabbits. One eye, randomly selected, received intraoperative application of MMC at the site of the implant plate for 5 min, via a 6 x 4 x 2 mm cellulose sponge saturated with 0.5 mg/ml of MMC. The opposite eye served as a control. MMC-treated and control eyes (five animals each group) were compared for intraocular pressure (IOP), resistance to flow, flow rates through the implant and histopathological findings at 2, 4, 6, 12, and 24 weeks postoperatively. Resistance to flow and flow rates through the implants were studied after opening the cornea and connecting the drain tube to a micromanometric system. RESULTS: Preoperative IOP did not differ between groups. MMC-treated eyes had lower levels of IOP than did controls at all postoperative times. The differences in IOP were statistically significant up to 8 weeks postoperatively. Resistance to flow was lower in MMC-treated eyes at all times studied, but the differences were statistically significant only at the time points of 2, 4, and 6 weeks. Flow rates through the implant bleb were always higher in MMC-treated eyes, and statistically significant differences were seen at 2, 4, 6, and 24 weeks. Histopathologically, MMC-treated eyes had thinner implant capsules with delayed maturation and less inflammatory infiltrate. CONCLUSION: MMC causes lower IOP and higher perfusion rates through the implant capsule at 2, 4, and 6 weeks postoperatively. Wound dehiscence, bleb leaks, and extraocular muscle injury were observed only in MMC-treated eyes.

Administration, Topical↗

PubMed1996

[Glaucoma and risk factors. Comparative study of cardiovascular risk factors in primary open-angle glaucoma, normal-pressure glaucoma and simple ocular hypertension].

This study compares the cardiovascular disease and risks factors, as well as ophthalmic findings of 20 primary open angle glaucoma, 23 low tension glaucoma and 11 ocular hypertensive patients. The low tension glaucoma group presents a high incidence of cardiovascular disease and risk factors, while the primary open angle glaucoma and the ocular hypertensive patients, present respectively, an average and low incidence of cardiovascular disease and risk factors.

Adult↗

PubMed1996

Vitreous opacities in phacolytic glaucoma.

BACKGROUND AND OBJECTIVE: To report five cases of vitreous opacification in phacolytic glaucoma (PG). PATIENTS AND METHODS: The records of patients with PG were retrospectively reviewed. A total of 135 eyes with PG were studied to determine the presence of vitreous opacification. RESULTS: Five eyes with PG demonstrated opacification of the vitreous, which was first noted at surgery and confirmed postoperatively. All patients had had symptoms of PG for 7 days or more (mean +/- SD, 10.6 +/- 2.4 days) before they sought medical attention. Three eyes had a hypopyon on preoperative examination; two of these eyes showed refractile crystals in the anterior chamber. The opacities resolved spontaneously in all five eyes over a period of 12 weeks and interfered with visual activity only in the immediate postoperative period. CONCLUSION: Vitreous opacification in PG is a self-limited process that may not require surgical intervention unless more rapid visual rehabilitation is desired. The vitreous opacification probably results from an exaggeration of the process causing the anterior chamber reaction.

Aged↗

PubMed1995

[Comparative study of administration time of mitomycin C in trabeculectomy: 2.5 or 5 minutes?].

BACKGROUND: To analyse the inocuity and the incidence of complications of a 0.2 mg/ml solution of Mitomycin C (M.M.C.), for two application time, 2.5 or 5 minutes. METHODS: 110 trabeculectomies were realised in 99 patients; they were high-risk (HR) patients in 66 cases, and low-risk (LR) patients in 44 cases. M.M.C. was used for 2.5 minutes in 44 cases (20 HR patients, 24 LR patients), and for 5 minutes in 66 cases (46 HR patients, 20 LR patients). RESULTS: In both groups HR and LR, there is no significant difference on the pressure lowering whether the 0.2 mg/ml solution of M.M.C. is used during 2.5 minutes or 5 minutes (Student t-test at 6 months: HR: p = 0.224; FR: p = 0.542). For the early and late complication in the HR group, there is no significant difference whether M.M.C. is used 2.5 or 5 minutes. In the LR group, there is a significant difference for hypothalamy (p = 0.035) and choroidal detachment (p = 0.027). In this LR group, there is no significant difference in the late complications. CONCLUSIONS: A 0.2 mg/ml solution of M.M.C., when indicated, may be used as well in the HR and LR group during 2'30". In the HR group, if there are several risk factors, we propose to adapt the application time between 2.5 and 5 minutes, and increase it by 1/2 or 1 minute for each risk factor.

Adult↗

PubMed1995

[Prostaglandins E2 and F2-alpha in uveitic glaucoma in the Lewis rat].

PURPOSE: In the preinflammatory phase of S-antigen (S-ag) induced uveitis, an ocular hypotension occurs between day 2 and day 6 after S-ag injection. To better understand this phenomenon, we studied the levels of prostaglandin E2 (PGE2) and prostaglandin F2-alpha (PGF2-alpha) in the aqueous humor of S-ag injected rats at various time points after induction of disease. METHODS: Twenty-five female Lewis rats weighting 150 to 175 gm were injected in the hind foot-pad with 50 micrograms of S-antigen. IOP was measured each day at 9 am with a Tono-Pen tonometer. Aqueous humor was collected at days 0, 2, 4, 6, 9, 14 and 18 after S-ag injection. PGE2 and PGF2-alpha were assayed in the aqueous humor using an enzyme immunoassay method. RESULTS: The concentration of PGE2 increased after day 6 and peaked at day 14 after S-ag injection (45.6 +/- 9.0 mu/ml vs 1.1 +/- 0.1 mu/ml in controls, P = 0.04). The peak of PGE2 corresponded to the maximum inflammation and ocular hypertension. PGF2-alpha was increased from day 2 to day 6, with a peak at day 6 after S-ag injection (128.0 +/- 51 pg/ml vs 56 +/- 2.0 pg/ml in controls, P = 0.047), which corresponded to the preinflammatory ocular hypotension. A second peak was observed at day 18 after S-ag injection (3643 +/- 824 pg/ml, P = 0.049), which corresponded to the cessation of intraocular inflammation and ocular hypertension. CONCLUSIONS: The early increased concentration of PGF2-alpha in the aqueous humor of rats with S-ag induced uveitis may explain the ocular hypotension observed from day 2 to day 6 after S-ag injection.

Animals↗

PubMed1995

Circadian rhythm of intraocular pressure: a rat model.

The purpose of this study was to examine whether there is a circadian rhythm of intraocular pressure (IOP) in the Lewis rat. Therefore, 20 Lewis rats (40 eyes) were subjected to an alternating 12-hour-light and 12-hour-dark cycle. Using a Tono-Pen 1, IOP was measured every 2 h between 6 a.m. and 12 midnight and every 3 h between 12 midnight and 6 a.m. for 2 consecutive days. These measurements in the Lewis rat revealed a reproducible circadian rhythm with a peak at 8 p.m. and a trough at 6 a.m. In conclusion, when using the Lewis rat as an animal model in longitudinal studies that involve the IOP, the IOP should be measured at the same time each day to correct for diurnal variations. Additionally, Lewis rats may be a useful model to study the causes of circadian rhythms of IOP and for pharmacologic studies of new glaucoma medications.

Animals↗

PubMed1995

Measurement of rabbit intraocular pressure with the Tono-Pen.

A Tono-Pen-1 (TP-1) and a Tono-Pen-2 (TP-2) were calibrated against direct manometry in the eyes of living rabbits to determine the accuracy of the Tono-Pen. Eighteen normal eyes of 10 rabbits were cannulated and connected to a pressure transducer with a chart recorder. Intraocular pressure (IOP) was increased from 5 to 40 mm Hg in 5-mm-Hg increments and from 40 to 80 mm Hg in 10-mm-Hg increments. After each incremental increase, IOP was measured first with a TP-1 and then with a TP-2. Plotting the mean Tono-Pen readings for each eye against the transducer pressure produced the following two regression line formulas: y = -0.613+0.790x (r2 = 0.97) for TP-1, and y = -1.45+0.824x (r2 = 0.97) for TP-2. Neither regression line was statistically different; p = 0.2 for the two slopes, and p = 0.24 for the y-axis intersection. The TP-1 and TP-2 can be used to rapidly and accurately measure the IOP in normal rabbit eyes. Tono-Pen readings do, however, significantly underestimate pressures in the range of 5-80 mm Hg. A table with 95% confidence intervals for corrected IOP readings obtained with the TP-1 or -2 is provided.

Animals↗

PubMed1994

Animal model for uveitic glaucoma.

BACKGROUND: This study was carried out in order to improve the understanding of the pathogenesis of uveitic glaucoma. METHODS: Uveitis was induced in 48 Lewis rats by S-antigen injection. Intraocular pressure (IOP) was measured by Tono-Pen-2 daily for 24 days in 16 animals. Histopathology was performed sequentially in 14 rats on days 3, 5, 7, 9, 12, 15 and 18 after S-antigen injection. Aqueous dynamics studies were performed on days 0, 3, 7, 14 and 21. Aqueous humor production was measured using an FITC-albumin dilution technique; outflow facility was measured using anterior chamber infusion with constant pressure. RESULTS: IOP decreased to a mean of 16.5 +/- 4.3 mmHg from days 2-5 after S-antigen injections from a mean pre-experimental value of 20.5 +/- 5.4 mmHg. IOP increased from days 6 to 20 (35.8 +/- 9.1 mmHg; P = 0.00001). Histopathologic study revealed inflammation of the anterior and posterior segments from days 9 to 21 after S-antigen injection. Aqueous humor production decreased and outflow facility increased at day 3 after S-antigen injection. At days 7 and 14 after S-antigen injection, acqueous humor production was increased while outflow facility remained normal or was decreased. CONCLUSION: This model of uveitis glaucoma is characterized by three overlapping phases: (1) ocular hypertension, (2) ocular hypertension associated with clinical and histologic inflammation and (3) anatomic sequelae of uveitis and variable IOP. This model permits in vivo studies of mechanisms of IOP change associated with uveitis.

Animals↗

PubMed1994

The detection of post-traumatic angle recession by gonioscopy in a population-based glaucoma survey.

BACKGROUND: Blunt trauma is responsible for most eye injuries in urban populations. Anterior chamber angle recession has been reported to be the most common sign of previous blunt trauma to the eye. The cumulative lifetime prevalence of post-traumatic angle recession has not been reported previously, and the relation between angle recession and glaucoma in a population-based setting is unknown. METHODS: As part of a population-based glaucoma survey, gonioscopy was performed on 987 (82.7%) of 1194 inhabitants of the village of Mamre, near Cape Town, South Africa, who were 40 years of age or older. RESULTS: Some degree of angle recession was identified in one eye of 60 people and in both eyes of 86 people. Men were affected more than three times as often as women in the fifth, sixth, and seventh decades. The cumulative lifetime prevalence of angle recession in this community was 14.6%. The prevalence of glaucoma in people with angle recession was 5.5% (8/146). Of 87 eyes with 360 degrees of angle recession, only 7 (8.0%) had glaucoma. Excessive alcohol consumption was significantly related to the presence of angle recession in women (P < 0.001). The prevalence of monocular blindness due to trauma was 2.5% (25/987). CONCLUSION: Although the importance of the study may be limited to this community, the findings suggest that future population-based studies of ocular trauma should include gonioscopy on all individuals examined. Secondary glaucomas, especially those related to trauma, should be screened for in developing countries when trying to establish the prevalence of potential visual loss from glaucoma.

Adult↗

PubMed1994

Intraocular pressure in Lewis rats.

PURPOSE: To perform noninvasive measurements of intraocular pressure (IOP) in rats, the Tono-Pen-1 and Tono-Pen-2 were calibrated against direct manometry. Normal values and the long-term fluctuations of IOP in Lewis rats were established. METHODS: For calibration, 24 eyes were cannulated and connected to a pressure transducer with a chart recorder. IOP was increased from 5 to 40 mm Hg in 5 mm Hg increments, and from 40 to 60 mm Hg in 10 mm Hg increments. After each incremental increase, IOP was measured with a Tono-Pen-1 and a Tono-Pen-2 tonometer. To determine normal IOP in Lewis rats, IOP was measured with a Tono-Pen-1 in 229 eyes of 115 rats, and a histogram of normal IOP was established. To ascertain long-term IOP fluctuations, the pressure in 52 eyes of 26 rats was measured every day between 8:30 and 9:30 AM for 7 consecutive days. RESULTS: Plotting the mean Tono-Pen readings for each eye against the transducer IOP produced two regression formulas: y = 1.819 + 0.711 x (r2 = 0.92) for Tono-Pen-1, and y = -1.291 + 0.784 x (r2 = 0.97) for Tono-Pen-2. The normal IOP in rats was 17.30 +/- 5.25 mm Hg (90% confidence interval: 7.28 and 26.98 mm Hg for the lower and upper limits of normal IOP). There was no long-term fluctuation in IOP (P = 0.55). CONCLUSIONS: IOP can be measured accurately in living rats with the Tono-Pen-1 or the Tono-Pen-2.

Animals↗