Ophthalmologe最新文献

Background and purpose: Aniseikonia as one of the major risk factors for asthenopic problems is mostly overlooked in modern cataract surgery. The purpose of this study was to develop a simple calculation scheme for clinicians to predict the object to image magnification in a pseudophakic eye with biometric data.

Methods: The calculation scheme for object to image magnification in the pseudophakic eye is based on a vergence calculation of the lens power with theoretical optical formulae. From the biometric data, which are typically derived from both eyes during lens power calculation, the vergences in front of and behind the 3 or 4 refractive surfaces of the pseudophakic eye model are used to predict the magnification for objects at infinity or objects located at a finite measurement distance (e.g. 5 m).

Results: With a formula-based lens power calculation a pseudophakic eye model is set up with 3 or 4 refractive surfaces (postoperative spectacle refraction; thick cornea described by anterior surface or thick cornea characterized by anterior and posterior surfaces; intraocular lens). The vergence in front of and behind each refractive surface is derived by means of linear Gaussian optics. The quotient of the product of all vergences in front of the surfaces and the product of all vergences behind the respective surfaces describes the object to image magnification of the eye. A comparison of the object to image magnification of both eyes yields the retinal image size disparity or aniseikonia. This calculation strategy is shown in a step-by-step approach exemplarily for the Haigis and Hoffer‑Q formulae (3 surfaces) and the Castrop formula (4 surfaces).

Conclusion: If during planning and lens power calculation biometry is performed for both eyes, ocular magnification of both eyes can be easily derived with this calculation scheme and aniseikonia can be extracted from a comparison of magnification of both eyes. Such a simple prediction should be established as a standard for precataract biometry and lens power calculation for early detection and avoidance of asthenopic complaints after cataract surgery.

Background: The dynamic contour tonometer PASCAL (DCT) is a direct noninvasive digital tonometer matching the corneal contour. We compared the DCT with the Goldmann applanation tonometer (GAT).

Methods: A total of 100 eyes were included in this prospective comparative clinical investigation and intraocular pressure (IOP) was measured with GAT and DCT before and after pars plana vitrectomy (ppV). Different intraocular endotamponades, such as gas and silicone oil were used. Preoperative IOP, changes in IOP postoperatively and intertonometer differences were measured.

Results: The preoperative mean IOP was 15.8 ± 5.2 mm Hg measured with the GAT and 17.5 ± 5.9 mm Hg with DCT. On the first postoperative day, in eyes with gas endotamponade the mean IOP rise was 2.5 mm Hg (p = 0.035) and 18 eyes were measured with an IOP of ≥ 25 mm Hg (19.1%; DCT). Postoperative IOP measured by GAT was 2.5 mm Hg lower and in eyes with gas endotamponade the GAT measured the IOP 3.0 mm Hg lower than the DCT. In eyes with a postoperative IOP above 20 mm Hg, the GAT measured the IOP 4.7 mm Hg lower compared to the DCT. Out of 18 eyes 10 with IOP ≥ 25 mm Hg were not recognized as hypertensive (≥ 25 mm Hg) by GAT. In 13% of the eyes the DCT measured at least 6 mm Hg higher IOP levels than GAT on the first postoperative day. In one extreme case with gas endotamponade, GAT underestimated the IOP by 12 mm Hg compared to the DCT.

Conclusion: The IOP spikes after ppV are a feared complication and can lead to irreversible visual loss. Depending on the endotamponade, GAT measures lower IOP than DCT, especially in IOP spikes caused by expansive gas endotamponade. Postoperative IOP measurement is important and readings between GAT and DCT can differ.

Relative anterior microphthalmos, nanophthalmos and high-grade hyperopia are small eyes with different characteristic morphological relationships between the anterior segment and axis length. This article discusses the intraoperative challenges and surgical approaches to solutions for cataract operations in patients with one of the three named morphological alterations. Additionally, the article addresses possible comorbidities including glaucoma and preoperative planning.

Background: Patients with iris defects suffer from severe visual impairment, especially increased glare sensitivity, and cosmetic disturbances. This can constitute a great psychological strain for patients. In the recent past the treatment consisted of iris print contact lenses, sunglasses and simple iris prostheses. The indications for surgical treatment are colobomas of the iris, aniridia, traumatic iris defects and persistent mydriasis. The aim of this review article is to investigate the surgical approaches, complications, functional and aesthetic outcome after implantation of an individual artificial iris prosthesis made from silicone.

Objective: Analysis of the literature on the topic of surgical iris reconstruction with an artificial iris in combination with the own experience in more than 120 patients treated by the author in the last 10 years.

Material and methods: The custom-made flexible silicone iris prosthesis ArtificialIris (HumanOptics, Erlangen, Germany) assessed in this review is an innovative and versatile option for surgical treatment of iris defects. Patients were examined before and after iris reconstruction with respect to feasibility, complications and outcome.

Results: Change of best corrected visual acuity, intraocular pressure, pupillary opening, glare, contrast sensitivity, endothelial cell count, anterior chamber depth, anterior chamber angle and patient satisfaction were assessed. Furthermore, complications and color match to the residual and fellow iris were assessed.

Conclusion: The implantation of an artificial iris is an effective option for the treatment of extensive traumatic iris defects and leads to an individual aesthetically appealing and good functional outcome as well as high patient satisfaction; however, this is an intervention that should not be underestimated because of a flat learning curve and various complications that can occur.