Star testing: a novel evaluation of intraocular lens optical quality.

BACKGROUND: Despite the importance of optical quality of an intraocular lens (IOL) on visual outcomes following cataract surgery, objective data on their optical quality are not readily available, and manufacturing standards are industry regulated. The star test is a classic test of optical quality based on examination of the Airy disc and expanded diffraction rings of a point source of light, used mainly for telescope and microscope objectives. METHODS: A physical model eye cell allowed star testing of IOLs under conditions similar to the optical environment in which they operate. 18 IOLs were tested and results compared to actual images produced by these lenses in the model eye cell. Quantitative measures of star testing performance were developed. RESULTS: The optical performance of the IOLs varied, some performing very poorly. Most lenses (13/17) performed better in reverse orientation, while aberrations induced by the haptics of foldable IOLs were also detected. There was excellent correlation between actual images formed and star testing parameters. CONCLUSION: Star testing IOLs was a novel biomedical application of a centuries old, inexpensive method. A concerning variation of optical quality was found, suggesting IOL optical performance data should be more readily available. Independent, authority mandated IOL optical quality standards should be developed, and results readily available to ophthalmologists.

Digital imaging of the human cornea in vivo with ultraviolet light.

We have a developed a novel and practical method of imaging the cornea under ultraviolet (UV) light using a digital medium. Wavelengths of 336-371 nm were used to illuminate the cornea. Images were recorded using a UV Nikkor lens and a digital charged coupled device (CCD). Images obtained showed ferritin lines not visible under white light. This study concluded that 336-371 nm is comparable to shorter wavelengths for the imaging of ferritin in the cornea and that a digital image capture system was comparable to that of film.

Otago Glaucoma Surgery Outcome Study: long term results of cataract extraction combined with Molteno implant insertion or trabeculectomy in primary glaucoma.

BACKGROUND/AIMS: To describe the long term results of cases of cataract extraction combined with either Molteno implant insertion or trabeculectomy for primary open angle glaucoma. METHODS: This prospective case series followed cases which had cataract extraction and Molteno implant insertion (45 eyes) or trabeculectomy (94 eyes) followed up for a mean of 5.3 years and 3.9 years respectively. RESULTS: Cataract extraction and Molteno implant insertion or trabeculectomy controlled the intraocular pressure at 21 mmHg or less with a probability of 1.00 (95% CI 0.93 to 1.00) at 10 years or more after operation and 0.94 (95% CI 0.89 to 0.99) and 0.73 (95% CI 0.46 to 0.99) at five and 10 years after operation respectively. CONCLUSIONS: Cataract extraction combined with insertion of Molteno implants or trabeculectomy controlled the intraocular pressure in 100% (45/45) and 94% (88/94) of cases respectively.

Long term follow up of bone derived hydroxyapatite orbital implants.

AIMS: To document the long term experience of bone derived hydroxyapatite orbital implants and compare results using scleral wrapped implants with those not using sclera. METHODS: This retrospective case series reviewed the long term follow up of 118 patients with 120 eyes which had undergone enucleation and bone derived hydroxyapatite orbital implant insertion at Dunedin Hospital from 1977 until 2000. Patient details were obtained from theatre records, case note review, patient interview and examination, interview of patient relatives, and family general practitioner records. RESULTS: Of the 120 eyes 84 had bone derived hydroxyapatite orbital implants with sclera and 36 without sclera. Follow up was 0.5-25 years (mean 8.9 years). 25 (19.3%) suffered minor complications of limited exposure of the implant which resolved spontaneously, with implant drilling or wound resuture. Nine (7.5%) suffered major complications requiring explantation. Major complications were more likely in cases with major tissue disruption, ischaemia, or inflammation. There were significantly fewer complications in the group where a bone derived hydroxyapatite orbital implant was implanted without a scleral covering (p<0.05). CONCLUSIONS: The placement of a bone derived hydroxyapatite orbital implant in the socket was associated with a low rate of long term complications and good cosmesis in most cases. The omission of a scleral covering over the hydroxyapatite sphere had some advantages and may prove to be the procedure of choice.

Anti-inflammatory fibrosis suppression in threatened trabeculectomy bleb failure produces good long term control of intraocular pressure without risk of sight threatening complications.

AIMS: To determine the long term outcome of systemic anti-inflammatory fibrosis suppression in cases of threatened trabeculectomy bleb failure in open angle glaucoma. METHODS: This prospective non-comparative case series followed 77 eyes of 63 patients which showed signs of threatened early bleb failure and were treated with oral anti-inflammatory fibrosis suppression of prednisone, a non-steroidal anti-inflammatory agent, and colchicine taken for a mean period of 6 weeks, in addition to standard postoperative topical treatment, for a mean follow up of 6 years. RESULTS: Trabeculectomy with anti-inflammatory fibrosis suppression controlled the IOP at < or =21 mm Hg with a probability of 0.91 (95% CI: 0.81 to 1.0) at 8 years and 0.89 (95% CI: 0.56 to 1.1) at 12 years. There were no reported cases of endophthalmitis, hypotonous maculopathy, late bleb leak, or serious systemic side effects. CONCLUSION: Anti-inflammatory fibrosis suppression provided good control of bleb fibrosis without risk of sight threatening complications in a patient group at high risk of bleb failure.

The pressure phosphene tonometer--a clinical evaluation.

AIMS: Pressure phosphene tonometry is said to assess intraocular pressure by inducing a pressure phosphene. This study compared the results of this relatively new technique with Goldmann applanation tonometry. METHODS: A total of 100 patients (196 readings) in a general ophthalmology clinic at Dunedin Hospital who consented to take part in this study were randomised to receive by different examiners either pressure phosphene tonometry by a Proview eye pressure monitor (Bausch & Lomb Inc., Tampa, FL, USA) or Goldmann tonometry first. There was no communication between the examiners regarding results. RESULTS: Of the 196 attempted readings, pressure phosphene tonometer readings were only able to be obtained for 136 eyes (69%) compared to all 196 (100%) eyes with the Goldmann tonometer. The mean IOPs were 18.5 mmHg using the pressure phosphene tonometer and 16.0 mmHg using the Goldmann tonometer. The mean difference was +2.43 mmHg (95% confidence interval: 10.37 mmHg below to 15.22 mmHg above Goldmann readings). CONCLUSION: This study found that 31% of patients could not perceive a pressure phosphene using the Proview eye pressure monitor. Data obtained from those who could perceive the phosphene indicated that large discrepancies between pressure phosphene tonometry and Goldmann tonometry were common.