Evaluating New Refractive Surgical Procedures: Free Market Madness Versus Regulatory Rigor Mortis

The Call of the Sirens: Ethically Navigating the Sea of Nonvalidated Therapies

Medical research and innovation are vital to the advancement of medicine and, ultimately, benefit society and individual patients. However, the ethical principles of beneficence, respect for persons, and justice must guide the development and implementation of new practices. Ethical codes governing clinical practice and research already warn practitioners to avoid the use of nonvalidated practices outside of controlled clinical trials. Nonetheless, lack of compliance with these codes places many patients at risk for harm. Ophthalmologists, as well as all physicians, must recommit themselves to these ethical principles and codes and establish more vigorous peer-review methods to protect patients from nonvalidated practices that are implemented without a scientific basis.

LASIK for hyperopia and hyperopic astigmatism--results of a pilot study

Laser-assisted in situ keratomileusis (LASIK) was evaluated in hyperopia and hyperopic astigmatism. LASIK was safe and effective in spherical hyperopia up to +5 D and acceptable in toric hyperopia up to +5 D but results were poor in hyperopia of more than +5 D.

Clear lens extraction to correct hyperopia

PURPOSE

To evaluate the effectiveness and safety of clear lens extraction with intraocular lens (IOL) implantation to correct hyperopia and to determine the most accurate and predictable method of IOL power selection.

SETTING

The Eye Institute of Utah, Salt Lake City, Utah, USA.

METHODS

The outcome of 20 phacoemulsification and IOL implantation procedures was assessed at a mean follow-up of 23.2 months (range 3 to 60 months). Intraocular lens power and predicted refraction were retrospectively evaluated in each eye with the SRK II and Holladay formulas with different attempted refractions based on the stabilized postoperative refraction.

RESULTS

Uncorrected visual acuity (UCVA) improved from 20/200 preoperatively to 20/30 postoperatively. At the final examination, 89% of eyes achieved 20/40 or better UCVA. All eyes had 20/25 or better best corrected visual acuity (BCVA). No eye lost two or more Snellen lines of BCVA. There were no surgical or postoperative complications. The Holladay formula was more accurate than the SRK II formula. With the Holladay formula aiming for -1.00 diopter (D), the predicted mean postoperative spherical equivalent would be -0.21 D +/- 0.89 (SD); with the SRK II aiming for -1.50 D, it would be +0.43 +/- 1.10 D. The Holladay formula reduced the chance of postoperative residual hyperopia.

CONCLUSION

Clear lens extraction with IOL implantation was an effective, safe procedure for the correction of hyperopia. However, this method was less accurate and less predictable for hyperopia below +3.00 D. With the Holladay formula aiming for -1.00 D, good visual and refractive results can be expected. Further study with a larger sample of patients and longer follow-up is needed to assess long-term safety and effectiveness.

Release of TGF-beta 1 and VEGF in tears following photorefractive keratectomy

PURPOSE

To study the presence and release of tear fluid transforming growth factor-beta 1 (TGF-beta 1) and vasoendothelial growth factor (VEGF) of 19 patients undergoing excimer laser photorefractive keratectomy.

METHODS

Tear fluid samples were collected with scaled microcapillary tubes preoperatively (Day 0) and on the first or second (Day 1-2) and seventh (Day 7) postoperative days. Since postoperative tear fluid flow was significantly higher, we calculated the release of both growth factors by multiplying the concentration by the tear fluid flow in the capillary.

RESULTS

The median tear fluid flow in the capillary was 8.1 microliters/ min (range 0.7-20.8) on Day 0, 46.3 microliters/min (3.1-135.1) on Day 1-2, and 10.2 microliters/min (1.8-65) on Day 7. The median TGF-beta 1 concentration and release values were: Day 0: 4.5 ng/ ml (0-23) and 24 pg/min (0-257), Day 1-2: 9 ng/ml (0-32) and 446 pg/min (0-4602; p = 0.0014), and Day 7: 6.5 ng/ml (0-44) and 53 pg/min (0-470), respectively. The median VEGF concentrations and releases were: Day 0: 19 ng/ml (14-23) and 128 pg/min (11-458), Day 1-2: 15 ng/ml (11-20) and 695 pg/ min (14-2567; p = 0.0007), and Day 7: 17.5 ng/ml (15-22) and 167 pg/min (27-1235), respectively.

CONCLUSIONS

TGF-beta 1 and VEGF are components of normal tear fluid. The significantly increased release of both growth factors after exeimer laser photorefractive keratectomy may influence the corneal wound healing process.