Journal of refractive and corneal surgery最新文献

Background: I have previously reported a new technique of suture fixation of a posterior chamber intraocular lens (IOL) to the iris through a limbal incision in the absence of a posterior lens capsule. This study evaluated the results of that technique as an alternative to anterior chamber lens implantation or suturing of a posterior chamber lens through the ciliary sulcus and sclera.

Methods: The clinical records of 30 consecutive eyes that underwent this procedure between September 1987 and February 1991 were studied retrospectively. Four sutures were attached to four holes in the optic of a posterior chamber IOL. Two sutures on straight needles were passed through a superior limbal wound, to the pupil, reaching the inferior iris to be tied onto this iris. The two upper sutures on curved needles were passed through the pupil and going to the superior iris and then tied.

Results: An anterior vitrectomy was done in the pupil in 18 (60%) eyes. The mean postoperative follow-up time was 40 months (range, 24 to 66 months). Nineteen eyes (63%) had visual acuities of 20/40 or better; and 10 eyes (33%) had visual acuities between 20/50 and 20/80. The remaining eye had persistent cystoid macular edema, proven by fluorescein angiography, with 20/100 visual acuity. No serious anterior segment complications occurred. There was mild pigment dispersion on the IOL in four eyes. Four eyes needed timolol drops to lower the intraocular pressure.

Conclusions: This technique offers a viable alternative to transscleral fixation of a posterior chamber IOL via a limbal approach.

Background: We designed an excimer laser keratomileusis delivery system to increase the regularity of the refractive cut surface and allow greater precision in the level and shape of the ablated zone.

Methods: A parallel faced corneal disc was produced by microkeratectomy from six human eyes and surgical keratectomy in 12 beagle corneas. A 193-nanometer excimer laser that was used to project an oval beam onto the corneal disc was rotated on a flat surface to ensure overlapping of the ovally ablated areas between pulses.

Results: Electron microscopy of eye bank lenticules demonstrated a circular smooth regularly concave ablation zone. Histological examination of nine clear corneas confirmed thinning of the stroma without fibroblastic reaction and no epithelial hypertrophy. Mean preoperative corneal power of 43.15 +/- 2.18 decreased postoperatively to 33.61 +/- 2.34.

Conclusions: The new technique of excimer laser keratomileusis has the advantage of a cut surface smoother and the clear zone is devoid of the stepwise concavity and irregularity seen in diaphragm based photoablation delivery systems.

Background: Noncontact laser photothermal keratoplasty may provide a new alternative for the treatment of myopia, hyperopia, and astigmatism. The purpose of this article is to study the refractive effect that laser photoablation keratoplasty is capable of producing on a normal human cadaver cornea, including the relationship between the keratometric changes and laser treatment parameters.

Methods: The human cadaver eyes were treated with a holmium laser (pulsed Ho:YAG, 2.10 microns, 250 microseconds) coupled to a maskable, polyprismatic delivery system mounted on either an optical bench or a slit-lamp microscope. Using a topographic videokeratography system, we first investigated the refractive effect that noncontact laser photothermal keratoplasty would produce on a normal cadaver cornea. We then studied the keratometric changes produced by different radiant exposure levels at a fixed treatment pattern, as well as by different treatment patterns at a fixed radiant exposure level. Finally, we studied the possible therapeutic application of laser photothermal keratoplasty for correcting high postoperative astigmatism on a cadaver eye model.

Results: For the single-pulse 3-millimeter ring of eight-spot treatment, the keratometric power of the cornea initially increased with the radiant exposure and peaked at 26 J/cm2. The refractive effect was increased by projecting an additional set of eight spots equidistant between the first eight spots on the same diameter ring. Eighteen J/cm2 was the minimal radiant exposure required to produce consistent and predictable keratometric changes. The corneas were flattened using treatment patterns smaller than or equal to 3 mm in diameter and steepened using treatment patterns larger than or equal to 5 mm in diameter. A transition zone between 4 and 5 mm was observed in which minimal and unpredictable keratometric changes of the central cornea occurred. The surgically-induced astigmatism (> 10.00 D) was corrected by progressive laser photothermal keratoplasty treatments.

Conclusions: Laser photothermal keratoplasty can acutely steepen and flatten the cornea in human cadaver eyes.

Background: After accommodative changes of endocapsular silicone lenses in presenile nonhuman primates had been confirmed by several authors, this pilot study was designed to evaluate the ability of an artificial lens to restore accommodation in the senile eye of a rhesus monkey that had previously lost most of its accommodative capability.

Methods: An injectable silicone lens was implanted in one eye of six rhesus monkeys who were older than 17 years. Accommodation was documented as the amount of decrease of anterior chamber depth after pilocarpine stimulation.

Results: Four months after surgery, the decrease of anterior chamber depth was higher in the operated eye with the silicone intraocular lens in the two monkeys who had marked presbyopic changes in the natural lens. One monkey was kept for more than 4 years, retaining a decrease of at least 0.5 mm with the silicone lens, whereas the natural lens failed to show any accommodative change.

Conclusions: These findings support recent reports that presbyopia is primarily a consequence of lenticular aging rather than ciliary muscle factors. A pliable injected lens may therefore have the potential to restore accommodation in the senile primate eye.