Accuracy and reliability of IOL master and A-scan immersion biometry in silicone oil-filled eyes

PURPOSE

To compare the accuracy and reliability of intraocular lens (IOL) master and A-scan immersion biometry in silicone oil (SO)-filled eyes.

METHODS

A prospective, consecutive, nonrandomized study was performed in 34 SO-filled eyes of 34 patients, who underwent a pars plana vitrectomy, with SO removal and cataract surgery, as well as IOL implantation. Both IOL master and immersion A-scan were performed to measure the axial length (AXL) before SO removal. Three months after removal of the SO, AXL measurements using IOL master and refraction was performed. Accuracy of the two techniques was determined by a mean postoperative AXL using an IOL master and reliability was determined by mean actual postoperative refractive error.

RESULTS

Preoperative mean AXL was 23.91±0.24 mm (range 21.33-28.61 mm) and 23.71±0.59 mm (range 19.27-36.18 mm) by IOL master and A-scan immersion, respectively. Postoperative mean AXL by IOL master was 23.90±0.23 mm (range 21.58-27.94 mm), which showed a statistically significant difference from the preoperative mean AXL by A-scan immersion (P=0.005). The AXL measurement by IOL master also was more accurate than A-scan immersion by Pearson's correlation (0.966 vs 0.410). For reliability of the two techniques, the predictive postoperative refractive error in A-scan immersion (mean 1.79±1.04 D, range -14.62 to 16.41 D) was greater than that in IOL master (mean 0.60±0.23 D, range -2.74 to 2.33 D), with a statistically significant difference (P=0.049).

CONCLUSION

IOL master had more accuracy and less deviation in predictive postoperative refractive error than A-scan immersion in SO-filled eyes.

Infectious uveitis: Recent advances in diagnosis and treatment

No abstract available.DOI: http://dx.doi.org/10.3126/nepjoph.v4i2.6534Nepal J Ophthalmol 2012; 4 (2): 215-216

HLA-B27-associated acute anterior uveitis in the University Referral Centre in North Thailand: clinical presentation and visual prognosis

BACKGROUND

Acute anterior uveitis (AAU) is the most frequent type of uveitis encountered in the west. Although human leucocyte antigen (HLA)-B27-associated ankylosing spondylitis was reported in South East Asia, it is not known whether HLA-B27-associated ocular disease is prevalent in Thailand.

METHODS

A prospective study of 100 unrelated blood donors and 121 consecutive patients with AAU was carried out. All people underwent HLA-B27 typing and full ocular examination. Radiological examination of the sacroiliac joints was conducted in patients with low back pain or arthralgias.

RESULTS

The prevalence of HLA-B27 was 10% among the blood donors in contrast with 44% in the AAU group (p<0.001). The clinical characteristics of HLA-B27-associated AAU were similar to those published throughout the world (unilaterality in 74%, hypopyon in 31%, recurrent AAU in 64%). However, the increased intraocular pressure (IOP) was more common in the HLA-B-27-negative group (p = 0.03) than in their HLA-B27-positive counterparts. At least 15% of the HLA B27-positive group had radiological signs of ankylosing spondylitis.

CONCLUSION

The prevalence of HLA-B27 in the population without uveitis in Thailand is about 10% and clinical characteristics of HLA-B27-positive AAU are similar to those reported in the west. In contrast with earlier reports, HLA-B27-negative AAU in Thailand was associated with increased IOP and should be further studied.

Keratometry and axial length in pigment dispersion syndrome: a descriptive case-control study

PURPOSE

Pigment dispersion syndrome and pigmentary glaucoma are characterized by loss of pigment from the posterior surface of the iris due to reverse pupillary block. This may be due to an anomalous relation between the position of the globe within the orbit, the axial length of the globe, and the corneal curvature. The authors compared axial length, keratometry, and exophthalmometry in patients with pigment dispersion syndrome and pigmentary glaucoma and in healthy controls.

METHODS

Thirteen pigment dispersion syndrome and pigmentary glaucoma and 17 controls underwent refraction, keratometry, A-scan and exophthalmometry. Patients with pigment dispersion syndrome and pigmentary glaucoma were selected in a university glaucoma practice, and controls were selected for their age and refraction from the staff of the hospital. Both groups were comparable in age and refraction.

RESULTS

Mean age of pigment dispersion syndrome patients and healthy controls was 46.54 and 41.82 years (P = 0.30), respectively, and mean refraction (spherical equivalent) was -4.53 and -4.32 diopters, (P = 0.84), respectively. No statistical differences were noted in axial length measured with A-scan (25.98 and 25.14, P = 0. 15) or anterior chamber depth and lens thickness. The pigment dispersion syndrome and pigmentary glaucoma group had flatter keratometry than the myopic controls. Mean keratometry was 42.39 +/- 1.77 and 44.34 +/- 1.50 (P = 0.003), respectively.

CONCLUSION

The results show that patients with pigment dispersion syndrome have flatter keratometry of approximately 2 diopters compared with age-matched myopic controls. This finding suggests a difference in architecture of the anterior segment.