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Wolfgang Haigis

Publications and source records attributed to Wolfgang Haigis.

4 recordsLinked to original sources
PubMed2003

Changes in macular thickness and depth of anterior chamber in patients after filtration surgery.

BACKGROUND: The prospective study was undertaken to analyze retinal thickness of the macula and anterior chamber depth in patients undergoing filtration surgery at different times of follow-up. METHODS: Forty-four patients (45 eyes) were included. The thickness of the fovea and the extrafoveal retina were measured using optical coherence tomography (OCT). Anterior chamber depth was determined using the IOLMaster. All standard clinical examination and measurements were performed prior to surgery, at the 2nd day (1-3 days), 1 week, 1 month and 3 months after surgery. RESULTS: Preoperative IOP under topical medication was 25.5+/-7.5 mmHg. IOP was significantly decreased at all postoperative visits ( P<0.0001): 10.8+/-5.9 mmHg at the 2nd day, 10.4+/-5.2 mmHg after 1 week, 11.7+/-4.4 mmHg after 1 month and 11.4+/-3.6 mmHg after 3 months. No patient in our study suffered from prolonged postoperative hypotony (IOP<5 mmHg). Foveal thickness at the 2nd day, 1 week and 1 month were elevated compared with baseline ( P<0.004). Macular thickness changed from 164+/-20 microm before surgery to 168+/-20 microm after 2 days, 170+/-21 microm after 1 week, 173+/-19 microm after 1 month and 165+/-16 microm after 3 months. Mean thickness of the extrafoveal retina did not change significantly. Also, there were no significant changes in anterior chamber depth. There was no significant correlation between reduction of IOP and retinal thickness or anterior chamber depth. CONCLUSION: The reduction of IOP after filtration surgery leads to a moderate increase in foveal retinal thickness over approximately 1 month and is not associated with shallowing of the anterior chamber, provided that prolonged postoperative hypotony is avoided with the surgical technique used.

Adult↗
PubMed2003

Corneal power after refractive surgery for myopia: contact lens method.

PURPOSE: To clarify the theoretical background of the rigid contact lens overrefraction (CLO) method to determine corneal power after corneal refractive surgery. SETTING: University Eye Clinic, University of Würzburg, Würzburg, Germany. METHODS: Using paraxial geometrical optics, the measurement situation for the contact lens method was analyzed and the definitions of corneal refractive power were reviewed. Based on the theoretical Gullstrand eye, model eyes were constructed, representing 1 emmetropic and 2 myopic eyes (primary refraction -5.21 diopters [D] and -10.25 D, respectively) before and after photorefractive keratectomy and laser in situ keratomileusis. In these eyes, the application of the CLO was mathematically simulated using Gaussian thick-lens optics and commercial ray-tracing software. RESULTS: The CLO method measured neither the equivalent (total) power nor the vertex (back) power of the cornea but rather the quantity 336/R(1C) (R(1C) = anterior corneal radius). Based on these results and the Gullstrand eye, new formulas are proposed to derive the equivalent power and vertex power of the cornea by the CLO method. CONCLUSIONS: Depending on whether intraocular lens calculation formulas are based on equivalent (total) corneal power or vertex corneal power, the respective new formulas for the CLO method should be applied in patients after corneal refractive surgery. An increase in prediction accuracy of the refractive outcome is expected.

Computer Simulation↗
PubMed2002

[Pitfalls of IOL power prediction after photorefractive keratectomy for high myopia -- case report, practical recommendations and literature review].

BACKGROUND AND PURPOSE: Published experience with eyes after keratorefractive correction of myopia indicates that insertion of the average keratometric readings into standard IOL power predictive formulas will frequently result in substantial undercorrection and postoperative hyperopic refraction or anisometropia after cataract surgery depending on the amount of myopia corrected previously. The purpose of this paper is to discuss the accentuated differences of various approaches to minimize IOL power miscalculations by describing a case report of a patient with excessive myopia as well as a review of the literature. PATIENT AND METHODS: A 50-year old lady presented for cataract surgery on her left eye after having PRK seven years ago elsewhere (refraction - 25.5 - 3.0/20 degrees, central keratometric power 43.0 diopters [D]). Central power before cataract extraction was measured to be 35.5 D (Zeiss Keratometer) and 36.5 D (TMS-1 topography analysis) and refraction was - 3.0 D (before onset of index myopia). Orbscan slit scanning topography analysis displayed an anterior surface power of 36.8 D and a posterior surface power of - 9.3 D. Total axial length was 31.93 mm (optical biometry using Zeiss IOL-Master). The contralateral eye after PRK suffering from a comparable excessive myopia had required an exchange of the IOL implant because of intolerable anisohyperopia of + 6.0 D after primary cataract extraction elsewhere. RESULTS: Corrected corneal power values for the left eye were calculated as follows: (1) spherical equivalent (SEQ) change at spectacle plane 19.0 D, (2) SEQ change at corneal plane 26.2 D, (3) separate consideration of anterior and posterior curvature 27.5 D, (4) consideration of the IOL power misprediction on the fellow eye 29.5 D, (5) subtraction of 24 % of the SEQ change at the spectacle plane from the actually measured keratometry value 29.7 D, (6) clinical estimate from regression analysis performed earlier 30.5 D, (7) change of anterior surface power 34.5 D. Deciding for a presumably "real" corneal power of 28.0 D the Haigis formula was used to aim for - 2.0 D since the patient preferred to read uncorrected. Thus, a 21.0 D IOL was implanted uneventfully in the capsular bag. The stable refraction postoperatively was - 3.5 - 1.0/20 degrees and visual acuity increased to 20/30. Therefore, the "real" power of that cornea must have been around 30 D. CONCLUSIONS: After corneal refractive surgery, various techniques to determine the current corneal power should be compared and the value around which results tend to cluster should be relied on to avoid hyperopia after cataract surgery with lens implantation. In those cases where keratometry and refraction before PRK/LASIK are available, the gold standard is still to subtract the change of the SEQ at the corneal plane from the preoperative central keratometric power, although in the present case report the subtraction of 24 % of the SEQ change at the spectacle plane from the measured corneal power value seemed to produce the best result. Pure subtraction of the SEQ change at the spectacle plane from the corneal power value before refractive surgery has to be avoided in eyes with excessive myopia. The most reliable corrected power value should be inserted in more than one modern third-generation formula (such as Haigis, Hoffer Q, Holladay 2, SRK/T) and the highest power IOL should be implanted. In all instances, the cataract surgeon has to make sure that the corrected K-reading is not wrongly re-converted within the IOL power calculation formula used.

Corneal Topography↗