[Evaluation and quality assurance of refractive surgery procedures by the German Ophthalmological Society and the Professional Association of German Ophthalmologists. Status: May 2011]

[Prevalence and age-related changes of corneal astigmatism in patients before cataract surgery]

BACKGROUND

The aim of this study was to determine the extent and the distribution of corneal astigmatism in patients awaiting cataract surgery in a mid-European tertiary clinic centre and hence to establish the demand for methods reducing corneal astigmatism.

PATIENTS AND METHODS

Keratometry measurements of cataract surgery candidates assigned to a university clinic between January 2013 and October 2014 were recorded and analysed retrospectively.

RESULTS

A total of 6900 eyes of 3450 patients with a mean age of 72.5 ± 12.2 were analyzed. The corneal astigmatism was more than 0.5 dioptres (D) in 5193 eyes (75.3 %), >1.0 D in 2641 eyes (38.3 %), >1.5 D in 1304 eyes (18.9 %), >2.0 D in 644 eyes (9.3 %), >2.5 D in 363 eyes (5.3 %), >3.0 D in 236 eyes (3.4 %) and >3.5 D in 149 eyes (2.2 %). With increasing age a shift from with-the-rule astigmatism towards against-the-rule astigmatism was observed.

CONCLUSION

Of the patients admitted for routine cataract surgery at our clinic, 2641 eyes (38.3 %) had an astigmatism greater than 1.0 D. Our data could be helpful in establishing a protocol for using toric intraocular lenses and to determine the costs.

[Current state of refractive surgery of the cornea and lens]

Refractive surgery includes all procedures which are primarily targeted at changing the refractive power of the eye. Currently laser-assisted in situ keratomileusis (LASIK) is indicated to correct myopia of up to - 8 D, hyperopia up to + 3 D and astigmatism up to 5 D. Photorefractive keratectomy (PRK) and laser epithelial keratomileusis (LASEK) are primarily recommended for myopia up to - 6 D and for greater refractive errors, phakic intraocular lenses (IOL) are the first choice (myopia greater than - 6 D and hyperopia greater than + 3 D). If presbyopia is present in addition to the high refractive error, refractive lens exchange is another alternative.

[Avoidance and management of complications in laser in situ keratomileusis]

Laser in situ keratomileusis (LASIK) is now considered to be a safe and effective standard procedure for surgical correction of low to medium ametropia. Nevertheless, as in any other surgical intervention complex courses may occur in single rare cases. Possible complications include, but are not limited to, optically effective errors, such as too small or decentered optical zones as well as intraoperative flap cutting errors and postoperative complications, such as inflammation (e.g. diffuse lamellar keratitis, DLK), epithelial or flap folds, epithelial ingrowths or iatrogenic ectasia. Compliance to standards for indications and treatment based on the current scientific knowledge can significantly reduce the occurrence of complications. These standards include adjustment of the optical zone to the mesopic pupil diameter, the application of state of the art eye trackers, careful performance of intraoperative and postoperative procedures by a surgeon experienced in the entire spectrum of ocular surgery, the possibility of treating complications directly on occurrence and, last but not least, conservative patient selection and choice of treatment.

[Intrastromal femtosecond laser-based presbyopia correction]

The surgical correction of presbyopia is gaining more and more popularity in the field of refractive surgery. Besides intraocular treatment with multifocal or accommodative intraocular lenses more and more corneal laser approaches are being established. These are performed either with the Excimer laser as laser in situ keratomileusis (LASIK) or the femtosecond laser. The femtosecond laser treatment is done purely intrastromally without dissection of the epithelium and is characterized by an extremely low risk of infection and inflammation. The procedure leads to a central corneal steepening with more prolate shape and increase in depth of field. This leads to a better uncorrected near visual acuity, however, corrected distance visual acuity might be reduced due to these changes.