Anatomic features of the optic disc and risk of progression in ocular hypertension

We evaluated characteristics of the optic disc in ocular hypertensive patients which might portend future glaucomatous damage. We included in this study 12 patients with an intraocular pressure > 21 mmHg who on follow-up showed signs of optic nerve head damage. Each of these patients were matched to an ocular hypertensive patient who remained stable for > 5 years. This study found that neither optic disc, neural rim or peripapillary halo areas, vein or artery diameter over non-atrophied or atrophied retinal areas, differed significantly between groups (p > 0.05, Wilcoxon signed rank test). However, peripapillary atrophy was greater in patients who showed signs of glaucomatous disc damage (1.757 +/- 0.36 mm2, p = 0.02, Wilcoxon signed rank test) compared to stable patients (1.064 +/- 0.79 mm2), although this finding was not significant after the Bonferroni correction. Patients with < 0.6 mm2 area of peripapillary atrophy (n = 6), however, did not suffer damage. This study suggests that a relationship between the extent of peripapillary atrophy and the chance of developing optic disc damage in patients with ocular hypertension deserves further study.

Reproducibility of the Glaucoma-scope in cadaver eyes

We evaluated the intra- and inter-observer variability of depth measurements of the optic disc in cadaver eyes using the Glaucoma-scope. Intra-observer variation of 10 separately captured images became significantly greater with increasing depth of the optic cup (p < 0.001). The standard deviation of depth measurements were 9.06 mu over the neural rim, 25.00 mu along the cup wall, and 40.94 mu at the bottom of the optic cup. However, intra-observer variation of a single captured image did not increase with greater optic cup depth. Intra-observer variation, but not inter-observer variation, generally was greater when measuring the superior than inferior optic disc (p < 0.05). This study suggests that when capturing separate optic disc images with the Glaucoma-scope, increased variation in depth measurements can be expected with greater optic cup depth and in the superior portion of the optic disc.

Results of combined phacoemulsification and trabeculectomy in patients with elevated preoperative intraocular pressures

PURPOSE

We evaluated the results of 17 consecutive patients with high intraocular pressures and visually significant cataracts who underwent combined phacoemulsification and trabeculectomy.

METHODS

We individually matched each patient by age, race, and intraocular pressure (trabeculectomy group only) to two control groups: group 1, patients who had combined phacoemulsification and trabeculectomy and whose intraocular pressures were controlled preoperatively (pressure </=18 mm Hg), and group 2, patients who had high intraocular pressures preoperatively and trabeculectomy alone. Only patients with chronic open-angle glaucoma undergoing initial filtration surgery were included.

RESULTS

One year postsurgery there was no statistically significant difference between study patients and either control group in terms of intraocular pressure (p > 0.05). Moreover, no statistical difference was observed between groups at 1 year postsurgery in number of glaucoma medications, bleb height or extent, anterior chamber depth, or bleb vascularity (p > 0.05). Additionally, both study and control patients had a statistically similar peak pressure the first month following surgery (p > 0.05). Complications were similar among groups.

CONCLUSION

This study suggests that patients with chronic open-angle glaucoma and high intraocular pressure may undergo combined trabeculectomy and phacoemulsification and achieve long-term postoperative intraocular control similar to those patients who have trabeculectomy only or a combined procedure and controlled preoperative pressure.

The effect of lifestyle on the relative risk to develop open-angle glaucoma

Patients may inquire how lifestyle or emotions may influence their intraocular pressure or risk for developing chronic open-angle glaucoma. Currently, little modification of lifestyle (including diet, drugs, emotion, activity, or risk factors for cardiovascular disease or diabetes) can be advised to reduce the risk of developing chronic open-angle glaucoma. In appropriate patients, however, suggesting limiting total-body inversion or isotonic exercise may help prevent a transient intraocular pressure increase. In patients who are in good general health, and are motivated, an aerobic exercise program might provide a small decrease in the intraocular pressure. Also, limiting cigarette smoking or alcohol consumption several hours before an ocular examination may help prevent a falsely altered intraocular pressure measurement. In the future, modifiable risk factors for chronic open-angle glaucoma may become known. This may give the patient more control over the disease by altering their lifestyle.

The efficacy of apraclonidine as an adjunct to timolol therapy. Apraclonidine Adjunctive Therapy Study Group

OBJECTIVE

To compare the intraocular pressure (IOP) lowering efficacy of 0.5% and 1.0% apraclonidine hydrochloride when used adjunctively with 0.5% timolol maleate in 129 patients.

DESIGN

A multicenter, randomized, double-masked clinical trial. Adult patients of either sex diagnosed as having either open-angle glaucoma or ocular hypertension were enrolled in the study. Patients using only 0.5% timolol maleate twice daily for at least 4 weeks and who had 8 AM IOPs of at least 22 mm Hg and no greater than 30 mm Hg 12 hours after dosing were eligible for the study. After 8 AM baseline IOPs were obtained while patients were taking timolol only, they were then randomized to receive either 0.5% or 1.0% apraclonidine twice daily in addition to their timolol. Intraocular pressures were measured at 8 AM (before morning dosing) and at 11 AM (3 hours after dosing) on days 14 and 90 and at 8 AM only on day 45.

RESULTS

Both concentrations of apraclonidine produced significant IOP reductions from baseline at all visits (P < .001). At 8 AM, after the nighttime dose, the additional mean IOP reduction from the timolol baseline ranged from 2.5 to 3.3 mm Hg (10.3% to 13.6% reduction, respectively). At 11 AM, 3 hours after the morning dose, the additional IOP reduction from the timolol baseline ranged from 4.7 to 5.2 mm Hg (20.0% to 21.7%, respectively). No difference in IOP reduction was observed between the 0.5% and 1.0% apraclonidine concentrations and no loss of IOP efficacy was observed for either concentration for the duration of the study. Sensitivity to 0.5% and 1.0% apraclonidine was observed in nine (13.8%) and 13 (20.3%) patients, respectively. Overall, therapy was discontinued owing to ocular or nonocular side effects with 0.5% and 1.0% apraclonidine in 14 (21.5%) and 16 (25%) patients, respectively.

CONCLUSIONS

We believe that 0.5% apraclonidine is equally effective as 1.0% apraclonidine when used twice daily as the first adjunctive drug to timolol. The drug effect is maintained for at least 90 days.

Magnetic resonance imaging in patients with low-tension glaucoma

OBJECTIVE

To study diagnoses and anatomic findings found on magnetic resonance imaging in patients with low-tension glaucoma.

PATIENTS

We included in this study magnetic resonance images of 20 consecutive patients with low-tension glaucoma. We individually matched each patient with low-tension glaucoma to a control with normal ocular findings who had magnetic resonance imaging for reasons unrelated to the visual pathway.

DESIGN

We studied axial and coronal images of the orbit and optic nerve with digitizing software (Image-Pro Plus, Media Cybernetics, Silver Spring, Md). Statistical evaluation was with a Wilcoxon Signed Rank Test for anatomic findings and a McNemar Test for diagnosis.

RESULTS

We found no difference between groups in the optic nerve diameter or length, the carotid artery area, or the distance from the optic nerve to the carotid artery (P > .05). Left optic nerve area was greater in the control patients than patients with low-tension glaucoma (P = .026). The prevalence of intracranial abnormalities, including meningioma, aneurysm, and arteriovenous abnormality, was similar between groups (P > .05). However, diffuse cerebral small-vessel ischemic changes were found more in patients with low-tension glaucoma (n = 8) than control patients (n = 1) (P = .0196).

CONCLUSIONS

This study proposes a hypothesis that cerebral small-vessel ischemia is more common in patients with low-tension glaucoma and potentially reflects indirectly a vascular cause of the optic nerve head damage at least in a subgroup of patients. Importantly, further research still is required to provide direct evidence for a vascular cause involved in low-tension glaucoma.

Correlation of pattern discrimination perimetry to the optic disc and visual field in ocular hypertensive and chronic open-angle glaucoma patients

We evaluated 19 ocular hypertensive and 32 chronic open-angle glaucoma patients to determine the correlation of pattern discrimination field loss to known markers of glaucomatous damage on the visual field and the optic nerve head. This study found no statistical association of the findings on the pattern discrimination perimeter to the areas of the optic disc, peripapillary halo, peripapillary atrophy, neural rim, or cup/pallor discrepancy (P > 0.05). In addition, no statistical relationship was observed to the diameters of the largest vein or artery in the inferior- or superior-temporal quadrant adjacent to the optic disc (P > 0.05). Between pattern discrimination and automated perimetry no agreement was observed in any visual field cluster (Glaucoma Hemifield Test) greater than that expected by chance alone (P > 0.05). When both visual function tests disagreed, the proportion of abnormal diagnoses in any cluster did not differ statistically between tests in chronic open-angle glaucoma patients (P > 0.05). However, in ocular hypertensive patients a greater proportion of abnormal diagnoses was observed with pattern discrimination perimetry (P < 0.03). This study suggests that pattern discrimination perimetry appears to measure a different physiologic property of the retina than does automated perimetry.

Prognostic factors and postoperative course following single-plate Molteno implantation

We evaluated potential preoperative and early postoperative prognostic indicators for chronic intraocular pressure control in 38 consecutive glaucoma patients undergoing single-plate Molteno implantation. Six months following surgery 22 patients had an intraocular pressure < or = 18 mm Hg and were considered successes. Twelve patients had an intraocular pressure > 18 mm Hg and were considered failures. Factors such as age, race, sex, type of glaucoma, phakic status, eye treated, intraocular pressure, bleb elevation, or number of glaucoma medicines were not significantly related to postoperative intraocular pressure control (p > 0.05). Postoperatively a significant difference in intraocular pressure was not observed between success and failure groups until three (13.8 +/- 5.4 versus 20.8 +/- 6.4 mm Hg, p = 0.010) and six (11.2 +/- 3.3 mm Hg versus 21.2 +/- 1.2 mm Hg, p < 0.001) months. Approximately 50% of patients who had an intraocular pressure > 20 mm Hg and 75% of those who measured < 20 mm Hg at any given examination in the early postoperative period were controlled six months postoperatively. Patients controlled at six months maintained control for as long as 43 months postoperatively. This study indicates that in the early postoperative period after a single-plate Molteno implant some patients have an ocular hypertensive phase but may ultimately be controlled, whereas most patients with an intraocular pressure within the normal range maintain control long-term.

Analysis of diode, argon, and Nd: YAG peripheral iridectomy in cadaver eyes

We compared semiconductor diode, neodymium (Nd): YAG and argon laser iridectomies performed in 14 cadaver eyes using Miyake videographic, histologic and scanning electron analysis. We found that the diode laser created an iridectomy in < 10 applications in blue, hazel and brown irides using 1000-1200 mW over 0.5 seconds. In hazel and blue irides the argon laser created iridectomies at parameters similar to the diode, but required multiple low energy burns in brown irides. Scanning electron microscopy showed pigment epithelial loss with the diode and Nd:YAG laser, and heaped up epithelium at the iridectomy site with the argon laser. Nd:YAG laser had the greatest iridectomy size. This study suggests a possible clinical advantage of diode versus argon laser iridectomies in reduced applications in brown irides and in preventing postoperative pigment occlusion. However, diode laser demonstrated no definite advantage over Nd:YAG laser.

Results of trabeculectomy combined with phacoemulsification versus trabeculectomy combined with extracapsular cataract extraction in patients with advanced glaucoma

We compared the results of trabeculectomy combined with phacoemulsification (n = 16) with those of trabeculectomy combined with extracapsular cataract extraction (n = 18). There was no significant difference between the two groups in terms of early or chronic postoperative intraocular pressure (IOP) control or in terms of the number of glaucoma medications prescribed postoperatively. However, by 12 weeks postoperatively, bleb height and extent were significantly greater in the phacoemulsification group. There was no significant difference between the groups in terms of postoperative spheroequivalent, astigmatism, or cylindrical axis. The mean final visual acuity, however, was less in the extracapsular group. We conclude that phacoemulsification combined with trabeculectomy offers a safe and effective technique to control postoperative IOP in patients with glaucoma.

Fornix- vs. limbus-based flaps in combined phacoemulsification and trabeculectomy

We studied prospectively the results of limbus-versus fornix-based flaps in patients undergoing combined trabeculectomy and phacoemulsification. We found no significant difference at six months postoperatively in the level of intraocular pressure between the limbus-(16.1 +/- 4.1 mm Hg) and fornix- (14.0 +/- 3.4 mm Hg, p = 0.161) based groups, or in the number of glaucoma medications (p = 0.0750). The highest intraocular pressure recorded within the first postoperative month was similar between groups (18.4 +/- 6.9 mm Hg for limbus and 18.5 +/- 5.5 mm Hg for fornix, p > 0.900). Postoperative bleb height, extent, and vascularity, as well as chamber depth were statistically similar between groups (p > 0.05). Postoperative complications were similar between groups. This study indicates that both fornix- and limbus-based flaps may be used safely and effectively when performing a trabeculectomy combined with phacoemulsification.

Influence of serous suprachoroidal detachments on the results of trabeculectomy surgery

We evaluated the influence of early serous choroidal detachments upon the results of trabeculotomy surgery. In 18 consecutive patients with serous choroidal detachments we found no significant difference in the intraocular pressure or number of glaucoma medicines from individually matched controls one year postoperatively. Final intraocular pressure was not correlated to the duration (p = 0.427), time of onset following surgery (p = 0.669), or size (p = 0.149) of the serous choroidal detachment. Prior to onset of the serous choroidal detachment the anterior chamber depth, bleb height, number of glaucoma medications, and intraocular pressure were statistically similar to the control group (p > 0.05). Following detachment, anterior chamber depth, and bleb height remained similar, but intraocular pressure fell from 9.4 +/- 6.5 to 4.6 +/- 4.1 mmHg (p = 0.025). Postoperative complications were similar between groups. This study indicates that serous choroidal detachments following trabeculectomy which are limited in size or duration are not associated with a worsening of long-term intraocular pressure control.

Filtration surgery in rabbits treated with diclofenac or prednisolone acetate

We performed filtration surgery in one eye of each of 28 rabbits. Either a nonsteroid (diclofenac) or a steroid (prednisolone acetate) was given as a postoperative antiinflammatory agent. On no examination day was there a significant difference in the intraocular pressure of the rabbits that had received diclofenac as contrasted with those that had received prednisolone acetate (P > .05, Student's t-test). Neither was there, based on log-rank life-table analysis, any significant difference between the two groups in terms of filtering bleb survival (P = .484). Finally, there were no significant differences on any examination day between the two groups in terms of bleb height or conjunctival injection (P > .05, Mann-Whitney U-test). We conclude that in this rabbit model for filtration surgery, the postoperative antiinflammatory effect of diclofenac was similar to that of prednisolone acetate. Because a nonsteroidal agent such as diclofenac that could provide an antiinflammatory effect sufficient to allow optimal bleb survival in humans, without the level of potential side effects of corticosteroids, might be clinically useful, further studies may be warranted.

Comparison of diode and argon laser trabeculoplasty in cadaver eyes

PURPOSE

To evaluate differences in the effects of diode and argon trabeculoplasty on cadaver eye trabecular meshwork.

METHODS

The argon laser was used at a 50 mu spot size, 500 to 100 mW of power, and a 0.1 second time interval, and the diode laser was used at a 0.1 to 0.2 second time interval, 100 mu spot size, and 400 to 1200 mW of power. Analysis was performed using videography, microscopy, and scanning electron microscopy.

RESULTS

This study found grossly that burns with the argon laser caused tissue blanching and pigment dispersion, whereas no reaction was observed with the diode laser. The diode laser made no observable histologic alterations, but the argon caused fragmentation and coagulation of trabecular beams. Scanning electron microscopy showed that the diode laser caused an area of trabecular beam coalescence measuring 50 to 100 mu in diameter with energies > or = 0.12 J. A surrounding zone of more superficial trabecular beam fragmentation measuring 200 to 400 mu in diameter also was observed. Similar energy levels from the argon laser caused hole formation 200 to 400 mu in diameter. Lower argon energy levels (0.05 J) caused inconsistent coalescence 50 to 100 mu in diameter similar to the diode laser.

CONCLUSIONS

This study suggests that in the trabecular meshwork the diode laser causes a reaction at, but not at less than, energy levels shown previously to produce a clinical ocular hypotensive effect. Also, at similar energy per area, the tissue effects of the diode and argon laser are comparable.

Evaluation of the whole-field scotopic retinal sensitivity tester in clinical glaucoma practice

We determined the results of routine whole-field scotopic vision testing in consecutive patients with ocular hypertension or glaucoma who underwent Humphrey automated perimetric testing and optic disc examination. In 39 ocular hypertensive patients we found a mean threshold of 16.7 +/- 7.4 dB and in 61 glaucoma patients, 20.7 +/- 7.8 dB. A learning effect was noted in ocular hypertensive (p < 0.05) but not in glaucoma (p > 0.05) patients. No association of scotopic threshold levels was observed to the intraocular pressure, age, race, sex, eye tested, number of glaucoma medicines, visual acuity, pupil diameter, lens clarity, medical history, cup-to-disc ratio, mean defect, or pattern SD (p > 0.05). The average threshold level in 30 control patients was 16.5 +/- 6.3 dB, which was not statistically different from the ocular hypertensive (p > 0.05), but differed from the glaucoma group (p < 0.05). The sensitivity of this test was 77% and the specificity 53.8% in separating glaucoma and ocular hypertensive patients. This study suggests that although diffuse scotopic sensitivity loss occurs in patients with glaucoma, much overlap exists with normal and ocular hypertensive individuals that limits whole-field scotopic vision testing diagnostic capability.

Postoperative prognostic indicators following trabeculectomy

We evaluated prognostic indicators for long-term filtration from the ocular examination within the first three months following primary trabeculectomy without antimetabolite therapy. We found that in patients who were more easily controlled at one year postoperatively (intraocular pressure < or = 16 mmHg and using 0-2 medications), compared to those who were more difficult to control (> 16 mmHg or on three medications), the intraocular pressure became significantly different between groups at three months and the number of glaucoma medications at eight weeks postoperatively. More easily controlled patients had greater bleb elevation by one month and extent of bleb formation at two weeks postoperatively. The presence of microcysts, anterior chamber depth, and avascularity did not differ between the two groups. This study suggests that differences in the ocular examination exist within the first three months following trabeculectomy which reflect the postoperative intraocular pressure control at one year.

Tight versus loose scleral flap closure in trabeculectomy surgery

Thirty-two consecutive trabeculectomy patients were randomized to receive a tight scleral flap closure (15 eyes) with postoperative laser suture lysis, or a loose scleral flap closure (18 eyes) to determine differences in the surgical results. Three months postoperatively no statistical difference in intraocular pressure (loose closure 15.1 +/- 3.3 mm Hg, tight closure 15.0 +/- 3.6 mm Hg, p > 0.05) or number of glaucoma medicines (loose closure 1.6, tight closure 1.3, p > 0.05) existed between treatment groups. In the early postoperative period, no statistical difference between groups was observed in the anterior chamber depth, visual acuity or intraocular pressure (p > 0.05). Laser suture lysis was performed without complication in nine patients with a statistically significant reduction in intraocular pressure (p < 0.01). This study suggests, by the technique used, that no obvious benefit exists in using a tight versus a loose scleral flap closure when performing a trabeculectomy.

Prediction of postoperative visual acuity in patients with total glaucomatous cupping using the Potential Acuity Meter and automated perimetry

We evaluated the effectiveness of using the Potential Acuity Meter (PAM) and automated perimetry to predict postoperative vision in 30 advanced glaucoma patients following combined cataract extraction and trabeculectomy. Using the binomial distribution at alpha = 0.05, PAM and automated perimetry individually were significantly useful in predicting postoperative vision of 20/40 or better. Automated perimetry, but not PAM, was useful in predicting worse than 20/40 vision. Used together, automated perimetry and PAM testing were significantly useful in predicting vision worse or better than 20/40.

Conjunctival structure and cell counts and the results of filtering surgery

We evaluated perioperative conjunctival biopsy specimens in 28 consecutive patients with primary open-angle glaucoma undergoing trabeculectomy who had not undergone previous intraocular surgery. We found six months postoperatively that the number of goblet cells was significantly greater (6.40 +/- 5.40 vs 1.68 +/- 1.60 per field of view; P = .004, Student's t-test) in patients with easier postoperative intraocular pressure control (intraocular pressure < or = 15 mm Hg with zero to two glaucoma medications) than in patients with more difficult intraocular pressure control (> 15 mm Hg with three or more glaucoma medications). No statistical differences between groups were observed in mast cells, neutrophils, eosinophils, macrophages, plasma cells, lymphocytes, or fibroblasts (P > .05). Also, no statistical difference between groups existed in conjunctival structure, including mucopolysaccharide and collagen composition, vascular density, or epithelial thickness (P > .05). This study suggests that the number of conjunctival goblet cells may be related to intraocular pressure control after trabeculectomy.

Trabeculectomy with 5-fluorouracil vs single-plate Molteno implantation

We compared the results achieved in 22 consecutive patients who underwent single-plate Molteno implantation, with those achieved in a matched group who had trabeculectomy with postoperative 5-fluorouracil. Six months following surgery, the average intraocular pressure (IOP) in the Molteno group was 15.4 +/- 8.0 mm Hg, and in the trabeculectomy group, 16.1 +/- 5.6 mm Hg (P = .920). A mean of 1.4 antiglaucoma medications were being used in each group (P = .776). Complications following Molteno implantation included six tube revisions and three flat anterior chambers; following trabeculectomy, eight serous choroidal detachments and nine positive Seidel tests. This study suggests that Molteno implantation and trabeculectomy with adjunctive 5-fluorouracil provide similar IOP control, but that the two procedures are associated with different types of complications.

The influence of age upon inflammatory cell counts and structure of conjunctiva in chronic open-angle glaucoma

We evaluated the influence of age upon conjunctival structure and number of inflammatory cells by studying perioperative conjunctival biopsies from 54 consecutive primary open-angle glaucoma patients undergoing initial filtering surgery (trabeculectomy alone or combined cataract extraction and trabeculectomy). All patients had received chronic topical glaucoma therapy for > 1 year. We divided the patients into three age groups for analysis: 40-60 (n = 10), 61-74 (n = 28), and > 75 (n = 16) years. We found no statistical difference (p > 0.05, chi-square) in cell counts of neutrophils, eosinophils, mast cells, macrophages, fibroblasts, lymphocytes, plasma cells and goblet cells across the three age groups. In addition, no statistical differences were observed between age groups in vascular density, epithelial thickness as well as mucopolysaccharide and collagen composition (p > 0.05, chi square). This study suggests that conjunctival structure and inflammatory cell counts change little with advancing age in primary open-angle glaucoma patients.