[Multifocal intraocular lens (MIOL) surgery in young non-presbyopic ametropes : Reasonable and safe?]

BACKGROUND

Refractive lens exchange and implantation of a multifocal intraocular lens (MIOL) is mainly advised for ametropes with presbyopia. Non-presbyopic young ametropes who wish spectacle-independence are usually treated with corneal refractive surgery or phakic lenses.

OBJECTIVES

This retrospective case series aimed to analyse the refractive and subjective satisfaction outcome after MIOL surgery in both eyes of non-presbyopic ametropes where other treatment options were not possible.

MATERIALS AND METHODS

This retrospective case series comprised consecutively treated 32 eyes of 16 patients (5 myopic, 11 hyperopic patients; mean age 31 ± 6 years) who wished spectacle-independence and thus received an aspheric bifocal biconvex refractive-diffractive single-piece MIOL (Acri.Lisa 366/809, Carl Zeiss Meditec AG). Refractive data prior to and after surgery as well as subjective satisfaction at the 1‑year follow-up examination were assessed.

RESULTS

Related to distance corrected near visual acuity myopic eyes had a median efficacy index (EI) of 0.92 (±0.20) and hyperopes of 0.91 (±0.12) (P = 0.415). For intermediate vision, in both groups a lower EI (<0.5; P = 0.188) resulted in lower subjective satisfaction, which was higher for near and distance vision. Some of hyperopic patients reported limitations in near and distance vision, only one hyperopic patient would not have chosen this surgery again. None had a related complication during the follow-up.

CONCLUSIONS

When neither laser refractive surgery nor implantation of a phakic lens is possible, young non-presbyopic ametropes do profit from MIOL surgery with an aspheric bifocal biconvex refractive-diffractive MIOL.

[Unilateral Solar Maculopathy after Gazing at Solar Eclipse]

A 43-year-old male patient with unilateral metamorphosia presented after gazing at an eclipse with only one eye. Damage of the macula was demonstrated funduscopically, with OCT and angiography. Six weeks after initial presentation and oral methylprednisolone therapy (40 mg/d for 10 days), the symptoms and the morphological changes decreased. Solar retinopathy is a photochemical alteration of the retina, usually seen after sun gazing. In younger patients, it mostly presents as bilateral solar maculopathy. Some patients exhibit partial or total recovery.

[Perspectives of laser-assisted keratoplasty: current overview and first preliminary results with the picosecond infrared laser (λ = 3 µm)]

BACKGROUND

This article provides a review of the current state of laser-assisted keratoplasty and describes a first proof of concept study to test the feasibility of a new mid-infrared (MIR) picosecond laser to perform applanation-free corneal trephination.

METHODS

The procedure is based on a specially adapted laser system (PIRL-HP2-1064 OPA-3000, Attodyne, Canada) which works with a wavelength of 3,000 ± 90 nm, a pulse duration of 300 ps and a repetition rate of 1 kHz. The picosecond infrared laser (PIRL) beam is delivered to the sample by a custom-made optics system with an implemented scanning mechanism. Corneal specimens were mounted on an artificial anterior chamber and subsequent trephination was performed with the PIRL under stable intraocular pressure conditions.

RESULTS

A defined corneal ablation pattern, e.g. circular, linear, rectangular or disc-shaped, can be selected and its specific dimensions are defined by the user. Circular and linear ablation patterns were employed for the incisions in this study. Linear and circular penetrating PIRL incisions were examined by macroscopic inspection, histology, confocal microscopy and environmental scanning electron microscopy (ESEM) for characterization of the incisional quality. Using PIRL reproducible and stable incisions could be made in human and porcine corneal samples with minimal damage to the surrounding tissue.

CONCLUSION

The PIRL laser radiation in the mid-infrared spectrum with a wavelength of 3 µm is exactly tuned to one of the dominant vibrational excitation bands of the water molecule, serves as an effective tool for applanation-free corneal incision and might broaden the armamentarium of corneal transplant surgery.

[Difference and distance between the central and thinnest points of the cornea: impact of refractive state, age and ocular side]

BACKGROUND

The aim of the study was to quantify the difference in corneal thickness between the central and thinnest points (∆PachyZ-PachyD), the distance between the center of the cornea and its thinnest point (vector length PachyD) and to explore the impact of refractive state, age and ocular side.

PATIENTS AND METHODS

This was a multicenter, retrospective, cross-sectional study and medical records of 16,872 eyes were reviewed. The Orbscan® (Bausch and Lomb) procedure was used for pachymetry and keratometry.

RESULTS

The results showed that ∆PachyZ-PachyD and vector length PachyD were higher in hyperopic eyes (∆PachyZ-PachyD: 11.99 ± 12.08 µm, vector length PachyD: 0.85 ± 0.44 mm) compared to myopic eyes (∆PachyZ-PachyD: 9.2 ± 7.86 µm, vector length PachyD: 0.7 ± 0.37 mm; p < 0.001). Refractive state, age and ocular side demonstrated an independent, statistically significant impact on ∆PachyZ-PachyD and vector length PachyD.

CONCLUSIONS

As a result of the significant impact of refractive state, age and ocular side on ∆PachyZ-PachyD and vector length PachyD, these variables should be considered in a normative data collection.

[Therapeutic excimer laser treatment of the cornea]

Concomitant with new innovations in the field of refractive surgery, therapeutic excimer laser applications like phototherapeutic keratectomy (PTK) and topography-guided customised ablation treatment are gaining high importance and undergoing rapid evolution. Nowadays, PTK is an effective treatment modality for superficial corneal pathologies. Primary indications are decreased epithelial adherence, superficial opacifications and an irregular corneal surface. For the right indication and successful treatment of corneal pathologies with PTK, a knowledge of the size, depth and nature of the pathology, as well as the refractive status of both eyes is important. Next to slit-lamp examination, objective measuring systems like the topography, confocal microscopy and the anterior segment OCT facilitate presurgical planning. Regarding the treatment procedure the surgeon can choose between a variety of methods. PTK can be combined with manual epithelial debridement or done by only using the excimer laser. In the case of an irregular corneal surface, depending on the pathology, masking fluids or topography-guided custom ablation protocols can increase the visual outcome. To avoid recurrence of the underlying pathology (e.g., corneal dystrophy, haze), the topical application of 0.02% mitomycin C for 20-60 seconds has proved to be a safe and effective procedure. If the surgeon considers all the patient-related factors carefully and manages to combine the available treatment options correctly, PTK embodies an effective and minimally invasive alternative to lamellar or penetrating keratoplasty.

[Infectious keratitis after LASIK--update and survey of the literature]

LASIK has become the preferred surgical procedure for the correction of refractive errors. Microbial keratitis is a rare but severe complication. The incidence of post-LASIK keratitis, (uni- and bilateral) is difficult to estimate. The risk of bilateral infection could until now only be approximated by calculating it from the risk of unilateral infection. Due to the fortunately low incidence of post-LASIK keratitis, large-scale studies are necessary to obtain valid statistical data. The American Society of Cataract and Refractive surgery (ASCRS) developed a post-LASIK infectious keratitis survey in 2001. 116 post-LASIK infections were reported by the members of the society. The calculated incidence was 0.035 % or 1 infection in every 2919 procedures. Llovet et al. found 9 patients (18 eyes) with bilateral post-LASIK keratitis out of 204 586 procedures (incidence 0.0084 %). Gram-positive bacteria and atypical mycobacteria are the most common causes for microbial post-LASIK keratitis. There is an increasing literature of post-LASIK case reports caused by rare or atypical species. Severe cases of keratitis are more often correlated with a prolonged onset of infection and caused by atypical species. An overview of the current literature and our own data regarding post-LASIK keratitis (uni-, and bilateral) are presented.

[Stem cell-based therapies for retinal disorders]

In the context of cell-based therapies for hereditary retinal dystrophies and other retinal disorders, interest has focussed on the therapeutic potential of embryonic and tissue-specific stem cells. Stem cells are characterised by their capacity for self-renewal and by their multipotentiality. Because of these properties, they can be expanded in vitro and eventually differentiated into "desired" specialized cell types. Stem cells are not only candidate cells for the development of cell replacement strategies, but are also interesting cells for the establishment of ex vivo gene therapies. Here, we discuss recent experimental work performed to evaluate the therapeutic potential of embryonic, mesenchymal, hematopoietic, neural and retinal stem cells for the treatment of inherited retinal dystrophies and other retinal diseases.