Intrastromal corneal ring segments: how successful is the surgical treatment of keratoconus?

This review evaluates the outcomes of intrastromal corneal ring segment [ICRS] implantation for the treatment of keratoconus considering a new grading system based on the preoperative visual impairment of the patient. Additionally, a five-year follow-up analysis of patients with stable and progressive keratoconus is performed in order to assess the long term stability of the surgical procedure. Corrected distance visual acuity decreased statistically significantly in patients with mild keratoconus [P < 0.01] but statistically significantly increased in all other grades [P< 0.05]. The improvement in visual acuity and the decrease of keratometric and aberrometric values were stable throughout a long period of time in patients with stable keratoconus. In patients with progressive form keratoconus, a significant improvement was found immediately after the procedure, however clinically relevant regression greater than 3 D was observed at the end of the follow up period

Cataract surgery with femtosecond lasers

Cataract surgery with femtosecond lasers is approaching its practical application in ophthalmology. These lasers, working in the near infrared wavelength [1030nm] can penetrate the transparent and even opaque tissues of the anterior segment of the eye, with limitations related to vessels and mineral opacities. Femtosecond lasers, guided by image systems can precisely outline the anatomy of the anterior segment of the eye, acting in a very precise way, performing corneal incisions, capsulorhexis, softening and breaking of the nucleus, which are essential steps in cataract surgery. In this article we summarize the four technologies available and approaching commercial application in the coming future. The main differences between the systems are based on the diagnostic imaging techniques, which might either be based on optical coherence tomography or the Scheimpflug principles. One model [the Technolas Femtec 520 F custom lens, 20/10 Perfect Vision], offers the possibility of combined use in corneal and intraocular surgery. While clinical studies are being performed with all of them, and most probably becoming available on the market during 2011 and 2012, the main problem of this emerging technology is its practical application as the increase in costs will affect their availability in the market of cataract surgery. Research is needed to confirm the practicality and the advantages of femtosecond laser cataract surgery over conventional surgery. Meanwhile, a new path for the future of cataract surgery is opening

Corneal optical quality following sub 1.8 mm micro-incision cataract surgery vs. 2.2 mm mini-incision coaxial phacoemulsification

To study and compare the effects of the micro-incision cataract surgery [MICS-sub 1.8 mm] and mini-incision coaxial phacoemulsification [2.2 mm] on the optical quality of the cornea characterized in terms of corneal aberrations. Fifty eyes underwent MICS and 50 mini-incision phacoemulsification, by the same surgeon. Both types of cataract surgery were performed using low ultrasound power and through a clear corneal incision, placed on the steepest corneal meridian ranging from 1.6 to 1.8 in MICS [Group I] and from 2.12 to 2.3 mm in mini-incision coaxial phacoemulsification [Group II]. Seidel and Zernike aberration coefficients and RMS values were obtained for a 6-mm pupil preoperatively and one month after surgery. The corneal astigmatism did not show statistically significant changes in either of the two groups-[MICS: -0.73 +/- 0.63, -0.65 +/- 0.53 D, P = 0.25], [mini-incision phacoemulsification; -1.21 +/- 1.52, -1.00 +/- 1.19 D, P= 0.12]. The total RMS remained unchanged after MICS [1.77 +/- 1.7, 1.65 +/- 1.3 micro m, P= 0.18] and mini-incision phacoemulsification [2.00 +/- 1.87, 2.09 +/- 1.8 micro m, P = 0.41]. Statistically significant changes were found for coma [P = 0.004] and higher-order aberrations [P < 0.00l], showing MICS significantly less changes in cornea. Both MICS and mini-incision phacoemulsification do not degrade the optical quality of the cornea. Both surgeries do not induce a modification of the corneal astigmatism, even in the axis. It seems that 2 mm is the limit around which no optical changes are induced by cataract surgery in the human cornea

Irregular astigmatism after corneal refractive surgery an overview of the state of the Art

Irregular astigmatism is a challenging problem for the refractive surgeon. The aim of this paper is to describe the authors' experience and a present a literature review of the latest advances in the diagnosis and management of this difficult complication. We present a compilation of the different alternatives to treat irregular astigmatism secondary to corneal refractive surgery, as well as an innovative method to quantify the degree of irregular astigmatism, taking into account the clinical symptoms and the corneal aberrometric data. The outcome of the different choices to treat irregular astigmatism are presented, from contact lens fitting to the most recent ablative techniques based on corneal wavefront. Although irregular astigmatism is still one of the worst complications of refractive surgery, the better knowledge of the causes, the enhanced diagnostic devices and the improvement of the refractive surgical techniques have given the refractive surgeon a wide set of alternatives to improve the patients visual performance, and to avoid unwanted litigations.

Photorefractive corneal procedures in patients with systemic diseases

This retrospective, non-randomized, non-comparative clinical study included 14 eyes of 7 patients who underwent laser in situ keratomileusis [LASIK] and 4 eyes of 4 patients who underwent photorefractive keratectomy [PRK] as a primary procedure to correct their myopia and astigmatism. All patients had a history of controlled systemic autoimmune diseases including rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis, psoriasis and Behcet's disease. The visual acuity, refraction, keratometric readings, slit-lamp biomicroscopy and corneal topography were assessed in these eyes at regular follow-up periods of 1, 3 and 6 months postoperatively. The mean pre-LASIK/PRK spherical equivalent [SE] decreased from -4.01 D +/- 1.51 standard deviation [SD] preoperatively to - 0.31 D +/- 0.47 SD by the end of the sixth postoperative month which was statistically significant. The mean preoperative uncorrected visual acuity [UCVA] was less than 20/200. Six months after LASIK/PRK procedure, UCVA was 20/25 that was also statistically significant. Retreatment for regression was necessary in 5 [27.7%] eyes at variable periods of time following the primary procedure. The procedures were done easily without any unusual intraoperative complications. The postoperative symptom suggestive of dry eye were not more than usual with the exception of one eye which developed exaggerated symptoms