Note on matrices of random numbers

The statistical and structural characteristics of 13 matrices of random numbers in which both the cells and the entries were randomly chosen are discussed. Each matrix was explored considering row means, standard deviations, and correlations as well as column means, standard deviations, and correlations. A study concerning the sequential arrangement of digits was performed by finding out in tables of random numbers how many times the values 0 to 9 are followed by any other digit. Analyses indicate clear factor structures when factor analyzing correlations of rows and of columns and when examining sequential arrangements, concluding that for a given set of digits it is possible to assert both randomness and nonrandomness depending on how the data are examined.

[Pain and zona ophthalmica]

Pain before and during Herpes Zoster is well known. A new antiviral therapy is suggested. Post-herpetic neuralgia remains more difficult to treat.

Angle-fixated Anterior Chamber Phakic Intraocular Lens for Myopia of -7 to -19 Diopters

PURPOSE

To assess the safety and efficacy of a second generation, anterior chamber phakic intraocular lens (Baikoff Model ZB5M) in patients with high myopia.

METHODS

One hundred and twenty-one patients (134 eyes) with myopia of -7.00 to -18.80 D were implanted with the ZB5M lens and followed for 18 to 52 months; the number of eyes evaluated was: 6 months (104 eyes), 1 year (91 eyes), 18 months (78 eyes), 2 years (68 eyes), and 3 years (35 eyes).

RESULTS

Postoperative spherical equivalent refraction averaged -1.00 D and the error in refractive correction (achieved minus intended) averaged -0.40 D during the first 2 years, increasing -to -1.30 D refraction and -0.60 D error in refractive correction at 3 years. At 2 years, approximately 40% of eyes had a spherical equivalent refraction within +/-0.50 D, and 65% within +/-1.00 D. The uncorrected distance visual acuity was 0.048 at baseline and 0.5 at 3 years; near visual acuity was 0.21 at baseline and approximately 0.7 over the 3 years of follow-up. Spectacle-corrected distance visual acuity at baseline was 0.54; it improved to 0.7. Near visual acuity was 0.65 at baseline and it improved to approximately 0.75. Endothelial cell counts in the central and peripheral cornea were reduced by an average 3.3% at 6 months, declining an additional 1% to 2% over the remaining follow-up period. Regression analyses indicated that most of the endothelial cell loss was due to surgery. Additional complications included halos/glare in 37 of 133 eyes (27.8%) and iris retraction with pupillary ovalization in 30 of 133 eyes (22.6%). The intraocular lens was exchanged in four of 133 eyes (3.0%) and removed in three of 133 eyes (2.3%), the latter because of halos (one eye) and a flat anterior chamber with severe inflammation (two eyes).

CONCLUSIONS

Implantation of the Baikoff ZB5M lens in the anterior chamber of phakic eyes significantly reduced high myopia and produced a stable refractive outcome over the 3 years, accompanied by marked improvement in uncorrected distance visual acuity and minimal, non-progressive damage to the corneal endothelium. Frequent complications included pupillary ovalization and halos/glare. Improvements in accuracy of IOL power calculations are needed.

Comparative clinical trial of AMO Vitrax and Healon use in extracapsular cataract extraction

This randomized, single-masked, multicenter clinical trial, comprising 95 patients enrolled at five sites, evaluated the performance of AMO Vitrax and Healon viscoelastic materials during cataract surgery. Patients were examined preoperatively and at one day, four days, one month, and three months postoperatively. The following measurements were recorded and analyzed: percentage of endothelial cell loss from preoperative to three months postoperative; change in intraocular pressure (IOP) from preoperative to 24 hours postoperatively; postoperative corrected visual acuity; subjective assessment of ability of viscoelastic to create and maintain tissue space; intraocular transparency; ease of evacuation. Three months postoperatively, endothelial cell loss was 4.9% (+/- 8.3%) for the AMO Vitrax group and 6.3% (+/- 10.5%) for the Healon group. One day postoperatively, IOP decreased by 1.6 mm Hg and increased by +1.1 mm Hg, respectively. Postoperative visual acuities were similar between the two groups at three months. Subjective assessment of transparency was higher for Healon. Assessment of tissue space maintenance was similar between the two materials. Healon was rated as slightly easier to evacuate.

Nonfreeze myopic keratomileusis for myopia in 158 eyes

BACKGROUND

A prospective evaluation of non-freeze myopic keratomileusis is reported.

METHODS

One hundred and fifty-eight eyes of 98 consecutive patients underwent nonfreeze myopic keratomileusis, with BKS 1000 (Eyetech-M.V.A.A.G, Balzers, Liechtenstein) refractive set. The preoperative myopia ranged from -6.25 to -28.00 D. Mean follow up was 591.3 days (range, 90 to 1500 days).

RESULTS

The logarithmic mean preoperative spectacle-corrected visual acuity was 0.48 +/- 0.31 (20/40), and 0.44 (20/50) +/- 0.30 after 2 years and longer, whereas mean uncorrected visual acuity was 0.32 +/- 0.28 (20/70) in 34 of 82 (41.5%) eyes. After 2 years and longer, 21 of 82 (25.6%) eyes were within 1.00 D of emmetropia, and 43 of 82 (52.4%) were within 2.00 D. The subjective spherical equivalent refraction confidence interval at 90% was 9.28 D (-6.85 to +2.43 D). No refractive instability was detected during follow-up. We detected a trend toward improvement of spectacle-corrected visual acuity with time. However, after 2 years and longer, there was an increase in astigmatism of more than 1.00 D, when compared to the preoperative values, and 14 of 82 (17%) eyes lost two or more lines of spectacle-corrected visual acuity (statistically significant: p < .01).

CONCLUSION

The nonfreeze myopic keratomileusis procedure, with BKS 1000, substantially reduces moderate to high myopia, but predictability of refractive outcome is only fair, and the frequency of optical complications including irregular astigmatism is higher than desired.

Detection of Toxoplasma gondii in aqueous humour by the polymerase chain reaction

Ocular toxoplasmosis is the most frequent infectious cause of chorioretinal inflammation in immunocompetent patients. Nowadays, the biological diagnosis of ocular toxoplasmosis requires serological tests and anterior chamber puncture to detect the local production of specific antibodies. A new technique is described to detect Toxoplasma in aqueous humour by a polymerase chain reaction in which the target is a specific ribosomal DNA segment. Sixty eight patients (71 eyes) were included; 59 (83%) eyes were suspected of having ocular toxoplasmosis. Of these 59 eyes, 15 (25.4%) had characteristic fundus lesions with obvious intraocular inflammation signs and 44 (75%) had retinal scar of ocular toxoplasmosis without clinically detectable inflammation. Twelve (17%) eyes had uveitis of non-Toxoplasma origin and constituted the control group. The parasite was present in aqueous humour in 20 (33.8%) cases. No false positives were detected. The sensitivity of the test is reduced by the low numbers of the sample. The combination of this technique with Witmer-Desmonts coefficient increases the probability of making a biological diagnosis of ocular toxoplasmosis. The physiopathological value of this technique is emphasised and the presence of tachyzoites in the anterior chamber is suggested. This should be a very promising technique for the diagnosis of ocular toxoplasmosis.

Results of 87 cases of intraocular lens implantation at the front of the whole capsular bag

To prevent or delay Elschnig pearl formation, we performed an unusual surgical technique on 87 patients: intraocular lens implantation at the front of the whole capsular bag. We tried to obtain tight adhesion between the anterior and posterior capsules so the lens epithelial cells could not proliferate and form Elschnig pearls. In fact, the patients exhibited no Elschnig pearls or Soemmering's ring, but developed large anterior capsular folds and a multilayer cell membrane between both capsules after two (three cases), six (19 cases), and 12 months (14 cases). This led to a decrease in visual acuity, and a Nd:YAG laser anterior and posterior capsulotomy was required in most cases (83%). Several months later, these eyes developed enormous Elschnig pearls emanating centrifugally from the laser opening, strongly suggesting that lens epithelial cells require aqueous humor for Elschnig pearl transformation. Since it is not yet possible to obtain perfect adhesion between anterior and posterior capsules, our results confirm the need to remove the anterior capsule after extracapsular cataract extraction.