Einfluss des Alters auf die optischen Aberrationen des menschlichen Auges

BACKGROUND

Currently the influence of age on corneal and ocular aberrations is still insufficiently known. The aim of this clinical study was to compare age-related aberrations of human eyes.

METHODS

In a prospective study 98 eyes of 49 healthy patients ranging from 17 to 65 years of age (38.6+/-10.0 years) were consecutively examined. The best corrected visual acuity ranged from 0.8 to 1.6; 48 eyes were emmetropic (SE+/-0.5 D), 42 eyes myopic (SE <-0.5 to -6.75 D), and 8 eyes hyperopic (SE >+0.5 to +3.88 D). The corneal aberrations were derived from corneal topography (Keratron Scout, Optikon). The measurement of ocular aberrations was performed with a Tscherning wavefront aberrometer (ORK, Schwind). The aberrations of the Zernike coefficients and RMS values (1st to 4th order) were determined.

RESULTS

The mean corneal and ocular Zernike coefficients of higher order were smaller than 0.2 microm. There was an evident decrease of wavefront aberrations with increasing order. Higher order corneal aberrations were larger than the corresponding ocular aberrations. With increasing age higher optical errors increased in complexity, and the correlation of corneal and ocular aberrations decreased with significant differences. Although the corneal ocular RMS value of the 3rd and 4th order correlated in the younger group (r=0.51, p=0.0001), there was no correlation in the older group (r=-0.48, p=0.832). The influence of age caused a significant increase of ocular aberrations of the 3rd and 4th order, in particular a tenfold extension of coma (C07) (p=0.002), a twofold extension of spherical aberration (C12) (p=0.0001), and an increase of the 3rd and 4th order RMS values (p=0.001).

CONCLUSIONS

Increased age induced an increase in optical aberrations of the eye, which demonstrates the influence of the lens on ocular aberrations. The combination of corneal and ocular diagnostic methods is recommendable for a better understanding of visual performance.

[Cataract surgery in patients with end-stage glaucoma]

BACKGROUND

The purpose of this study was to assess the benefit of cataract surgery in patients with advanced cataract and glaucoma.

METHODS

In a prospective study, we investigated 12 consecutive patients (12 eyes). Inclusion criteria were the diagnosis of cataract and end-stage glaucoma with a cup-disc ratio (CD) of 0.9-1.0 and marked visual field defects with partially preserved central function. Preoperatively, at the third postoperative day and after 6 months (2-11 months), the visual acuity (V), the intraocular pressure (IOP), the number of antiglaucomatous drugs and the visual fields were assessed. Furthermore, the surgical procedure and possible complications were noted. In all patients cataract surgery was performed with topical anaesthesia.

RESULTS

10 patients were treated with cataract surgery alone, whereas 2 patients underwent combined cataract and glaucoma surgery. The mean visual acuity improved significantly from 0.3 to 0.5 (p = 0.007). Additionally a significant intraocular pressure reduction of 4.4 mm Hg (p = 0.007) was observed. The number of antiglaucomatous drugs decreased from 1.5 preoperatively to 0.8 postoperatively. The mean deviation (MD) improved from -27.5 dB up to -26.4 dB (p = 0.036) after 6 months.

CONCLUSION

Patients with progressive cataract and end-stage glaucoma can benefit from cataract surgery. Although marked visual field defects were present, an increase in visual acuity as well as a decrease of intraocular pressure may be achieved without worsening of the visual fields.

[Functional results after intraocular lens implantation with or without blue light filter: an intraindividual comparison]

BACKGROUND

The new generation of intraocular lenses (IOL) with an additional blue light filter has a slight yellowish colour (compared to the IOLs with only a UV filter) due to its different light transmitting properties. This could have an effect on contrast sensitivity and subjective visual perception.

PATIENTS AND METHODS

In this intraindividual prospective comparative study including 14 cataract patients without further ocular pathology, a blue light filtering IOL (SN60AT, Alcon) was implanted in one eye and 1 month later a conventional single-piece IOL (SA60AT, Alcon) was fitted into the fellow eye. The visual acuity and the clinical findings were assessed at one day and four weeks post-operatively. Contrast sensitivity was tested under defined mesopic (6 cd/m(2)) and high mesopic (18.8 cd/m(2)) light conditions in the Ginsburg Box using the Functional Acuity Contrast Test (F.A.C.T.). Furthermore, subjective differences in the visual perception of both eyes were noted.

RESULTS

The contrast sensitivity testing 1 day and 1 month postoperatively, revealed no statistically significant differences (P > 0.008) between both IOL types for all spatial frequencies (1.5/3/6/12/18 cpd) and light levels. 13 patients (85 %) reported no differences in the colour perception of both eyes, and none had visual disturbances.

CONCLUSION

This intraindividual comparison revealed no relevant differences concerning mesopic contrast sensitivity and the subjective visual perception after implantation of one IOL with or without a blue light filter.

[Covered sclerotomy for fistulating glaucoma surgery]

BACKGROUND

Covered sclerotomy was developed as a minimally invasive modification of filtering glaucoma surgery. In this prospective study the clinical results are compared after one year.

PATIENTS AND METHODS

58 eyes with advanced glaucoma were studied. 32 eyes had a covered sclerotomy (ST) and 26 had an ST with viscoelastic filling of the anterior chamber in order to reduce the postoperative hypotony rate (ST+H). The ST procedure consisted in the preparation of a 4-mm corneoscleral tunnel incision with a T-shaped 1.75-mm wide perforation and radial transection of the tunnel floor.

RESULTS

The preoperative intraocular pressure (IOP) was on average 30 +/- 8.5 mmHg (ST) and 26 +/- 8.3 mmHg (ST+H). After 1 year the IOP decreased significantly (P < 0.05) to 17 +/- 3.7 mmHg (ST) and 17 +/- 2.9 mmHg (ST+H). The mean IOP reduction was 37 % (ST) and 30 % (ST+H). Revisions were required in 37 % (ST) and 15 % (ST+H) of the cases. The postoperative hypotony rate was 34 % in both groups. The number of morphologically functional filtering blebs was 60 % (ST) and 70 % (ST+H) after one year.

CONCLUSIONS

The covered sclerotomy required minimal surgical manipulations of the conjunctiva and sclera. After 1 year a significant reduction of the IOP was achieved. However, the occurrence of bleb scarring could not be lowered compared to trabeculectomy. Therefore further modifications with the primary application of antimetabolites are planned.

OCT-Goniometrie vor und nach Iridotomie beim Engwinkelglaukom

PURPOSE

Visualization of the anterior chamber angle is an important diagnostic method in patients with angle-closure glaucoma. In this study, optical coherence tomography (OCT) was used to image the angle width, the iris configuration, and the iris thickness in patients with angle-closure glaucoma.

METHODS

Thirteen eyes of 11 patients suffering from angle-closure glaucoma were studied with slitlamp-adapted OCT. All patients were treated with Nd:YAG laser iridotomy. The angle width ( degrees ), the angle opening distance (AOD) (microm), and the iris thickness (microm) were measured with OCT. The configuration of the iris was classified as steeply convex, convex, or flat.

RESULTS

The mean angle width was preoperatively 5.1+/-5.0 degrees (0-15 degrees ) and enlarged significantly (p=0.007) to 10.4+/-5.5 degrees (0-19 degrees ) postoperatively. The AOD changed from 71+/-55 microm (0-157 microm) preoperatively to 143+/-74 microm (0-256 microm) postoperatively (p<0.001). The mean iris thickness was 338+/-33 microm. With the exception of two eyes the predominant iris configuration changed from convex to flat.

CONCLUSIONS

OCT allowed visualization and noninvasive assessment of the anterior chamber angle region in patients with angle-closure glaucoma. Our results suggest that goniometry with OCT could improve the evaluation in patients with narrow or closed anterior chamber angles.

[Optical quality of the cornea following incisional correction of astigmatism]

BACKGROUND

Unilateral lamellar keratotomy (LKT) and curved dual lamellar keratotomy (BLK) were compared to evaluate the influence of incisional correction of astigmatism on the optical quality of the cornea.

PATIENTS AND METHODS

Forty-six patients with a preoperative astigmatism greater than 1.5 D were studied. LKT was performed on 30 eyes during cataract surgery and 20 eyes were treated with a BLK. Preoperatively and 4 weeks after surgery the corneal topographical data were analyzed with ray tracing in a 3-mm optical zone. The potential visual acuity (PVA) and the optical distortion (OD), which is represented by the width of the point spread in the optical center, were calculated as parameters for the optical quality.

RESULTS

The mean surgically induced astigmatism was 2.6+/-1.5 D for the LKT group and 3.5+/-1.4 D for the BLK group. The PVA decreased significantly in the LKT group from 1.2+/-0.2 to 1.0+/-0.3 (p=0.008), whereas in the BLK group the PVA remained unchanged (p=0.916). The OD increased from 6.6+/-0.9 microm to 7.9+/-2.0 microm (p=0.007) in the LKT group. In the BLK group the values were stable (p=0.843).

CONCLUSIONS

The optical quality of the cornea decreased after unilateral keratotomy in the early postoperative period. Thus, optical quality values should also be considered in incisional correction of astigmatism.