Preoperative ultrasound biomicroscopy to assess ease of haptic removal before penetrating keratoplasty combined with lens exchange

Ultrasound biomicroscopy study of the Verisyse aphakic intraocular lens combined with penetrating keratoplasty in pseudophakic bullous keratopathy

PURPOSE

To evaluate anterior segment modifications after penetrating keratoplasty (PKP), previous anterior chamber intraocular lens (IOL) removal, and Verisyse IOL (AMO) implantation over the iris or under the iris for the treatment of pseudophakic bullous keratopathy (PBK) using ultrasound biomicroscopy.

SETTING

Department of Ophthalmology, Poitiers University Hospital, Poitiers, France.

METHODS

A prospective randomized comparative case series included 27 patients (27 eyes) with PBK who had PKP and implantation of a Verisyse VRSA54 aphakic IOL. The IOL was implanted over the iris in 13 patients (Group A) and under the iris in a reversed position in 14 patients (Group B). Ultrasound biomicroscopy scans 6 months after surgery measured central anterior chamber depth (ACD), iris thickness (IT), distance of the haptics from the corneal endothelium (CED), distance of the haptics from the ciliary body (CBD), angle opening distance (AOD) 500 mum from the scleral spur (AOD500) and the iridocorneal angle theta on the 4 o'clock meridian lines (AOD3; AOD9; AOD12; AOD6/theta12, theta6, theta3, theta9).

RESULTS

No significant difference was found in IT, CBD, or AOD12 between Group A and Group B (P >.05). In Group B, the mean ACD was deeper by approximately 55% (P = .008); CED3 was larger by 69% (P = .0162), CED9 by 80% (P = .0128), AOD3 by 57% (P = .0309), AOD9 by 140% (P = .0057), and AOD6 by 44% (P = .0399); and theta3 was wider by 52% (P = .046), theta9 by 123% (P = .0068), theta12 by 50% (P = .0492), and theta6 by 81% (P = .0237).

CONCLUSION

Ultrasound biomicroscopy showed that in eyes that had PKP with Verisyse IOL enclavation to the posterior plane of the iris, which involved posterior translation of the iridal plane, the ACD was significantly deeper and the CED and AOD were significantly larger than in eyes with anterior enclavation of the IOL.

Ultrasound biomicroscopy and Scheimpflug photography of angle-supported phakic intraocular lens for high myopia

PURPOSE

To evaluate the equivalence of Scheimpflug photography (SP) and ultrasound biomicroscopy (UBM) in determining corneal epithelium-intraocular lens (IOL) and border IOL-iris distances.

SETTING

Universität Erlangen-Nuremberg, Erlangen, Germany.

METHODS

In 26 eyes of 17 patients who had a NuVita MA20 angle-supported anterior chamber intraocular lens (Chiron-Domilens), SP and UBM were used to evaluate the distance between the endothelium and the anterior IOL face in central and peripheral regions (12 o'clock and 6 o'clock positions) and between the border of the anterior IOL face and the iris. The Wilcoxon test was used for statistical analysis.

RESULTS

The mean central endothelium-anterior IOL face distance was 2.01 mm and 2.00 mm by SP and UBM, respectively. The mean peripheral endothelium-anterior IOL border distance was 1.28 mm and 1.58 mm, respectively, and the mean peripheral anterior IOL face-iris distance, 0.89 mm and 0.75 mm, respectively.

CONCLUSIONS

The difference between the 2 methods in the central endothelium-anterior IOL face distance was not significant (methods were equivalent), but the difference in the peripheral endothelium-anterior IOL face distance was. This may be the result of difficulty in obtaining the exact transition point between the IOL and the haptics by SP examination. The difference between the 2 methods in the IOL border-iris distance was also significant because of the irregularity of the iris surface; therefore, measurements were performed at different sites along this structure. The significant differences in the peripheral endothelium-IOL and IOL border-iris distances indicate that although both methods are useful, they are not equivalent.

Predicting sulcus size using ocular measurements

PURPOSE

To predict sulcus size using ocular measurements.

SETTING

Michel Pop Clinics, Montreal, Quebec, Canada.

METHODS

Forty-three eyes were evaluated using several techniques. Ultrasound biomicroscopy (UBM) echograms were taken to measure the anterior chamber depth (ACD), sulcus size, and central corneal thickness. The limbus size was measured with a caliper. Axial length, ACD, and pachymetry were measured by contact ultrasonography. Refraction and corneal power were also evaluated.

RESULTS

The coefficient of linear regression was 0.05 between the limbus and the sulcus size (P =.78), 0.76 between ultrasonography and UBM ACD measurements (P <.001), and 0.69 between ultrasonography and UBM pachymetry (P <.001). Paired t tests showed that ultrasound and UBM ACD measurements were not statistically different (P =.70) but that ultrasound and UBM pachymetry measurements were (P <.001). The sulcus versus limbus difference was 0.6 mm for myopia and 0.3 mm for hyperopia. A backward elimination multiple regression performed with all measures to predict sulcus size resulted in the following formula: Sulcus size = 18.9 - 0.023 x sphere + 0.15 x mean keratometry (R = 0.49; P =.005; statistical power = 0.89; standard error of estimate = 0.5 mm).

CONCLUSION

Traditional estimation of sulcus size through limbal measurement is inadequate because limbus size alone cannot predict sulcus size. A general formula using the sphere and the mean corneal power can help predict sulcus size. Corneal power was significantly and negatively correlated with sulcus and limbus size as well as sphere. The standard error of sulcus measurement by UBM was 0.4 mm.

Use of ultrasound biomicroscopic evaluation in preoperative planning of penetrating keratoplasty

PURPOSE

To evaluate the use of ultrasound biomicroscopy (UBM) in examining the status of anterior-segment structures in eyes with corneal opacification.

METHODS

Evaluation with UBM was performed between 1 and 2 weeks before surgery in 21 patients (21 eyes) with corneal opacities who were scheduled for penetrating keratoplasty. UBM findings were correlated with the findings noted during penetrating keratoplasty. The efficacy of UBM evaluation was calculated in terms of positive and negative predictive values (PPVs and NPVs) for the presence or absence of each finding.

RESULTS

Seventeen eyes had either aphakic or pseudophakic bullous keratopathy (ABK or PBK). UBM findings of anterior synechiae, peripheral anterior synechiae, posterior synechiae, peripheral and sector iridectomies positively correlated with those observed during surgery in five (55.6%) of nine locations, 19 (73.1%) of 26 locations, 12 (80%) of 15 locations, eight (88.9%) of nine locations) and six (85.7%) of seven locations, respectively. The NPVs for these findings were 100%, six (54.5%) of 11 locations), 10 (71.4%) of 14 locations, 12 (100%) of 12 locations, and 14 (100%) of 14 locations, respectively. Correlation for findings pertaining to the posterior capsule (PC) were presence of PC/PC remnants [PPV, 13 (92.9%) of 14 locations; NPV, two (66.7%) of three locations], presence of central PC tears [PPV, two (66.7%) of three locations], intactness of PC [PPV, six (85.7%) of seven locations], and PC thickening [PPV, 13 (81.25%) of 16 locations; NPV, four (100%) of four locations]. For vitreous in the anterior chamber, the PPV was eight (100%) of eight locations, and NPV was 12 (92.3%) of 13 locations. Pseudophakos-related information in eyes with PBK showed a PPV of 100% for presence, centration, and anatomic location (seven of seven, four of four, and seven of seven locations, respectively).

CONCLUSION

In eyes with corneal opacity, UBM determines the status of various anterior-segment structures. It is thus a useful adjunct in the preoperative planning and prognostication of patients requiring penetrating keratoplasty.