Evaluation of macular function and morphology following accelerated collagen cross-linking in progressive keratoconus

PURPOSE

To assess any changes in macular function and morphology in patients with progressive keratoconus undergoing accelerated corneal cross-linking (CXL).

METHODS

This prospective case series included 9 eyes of 8 patients with progressive keratoconus undergoing CXL using a high intensity accelerated protocol (9 mW/cm² for 14 min) with a total surface dose of 7.5 J/cm². Visual acuity assessment, slit lamp biomicroscopy, dilated fundoscopy, corneal tomography, multifocal electroretinography (mfERG) and spectral domain optical coherence tomography scan were performed at baseline, 2 weeks and 6 weeks postoperatively.

RESULTS

Uncorrected and corrected distance visual acuity did not change significantly at 2 weeks and 6 weeks following accelerated CXL compared to baseline. Retinal response density (RRD) of mfERG significantly decreased at 2 weeks postoperatively compared to baseline (p = 0.008) but did not differ from the baseline value at 6 weeks postoperatively in the fovea (ring 1) (p = 0.95). Similarly, P1 latency significantly decreased at 2 weeks (p = 0.04) but did not change at 6 weeks (p = 1.00) postoperatively compared to baseline in the fovea. No changes in RRD or P1 latency were observed in the retinal rings surrounding the fovea (rings 2 to 5). Central foveal thickness did not change at 2 weeks and 6 weeks postoperatively compared to baseline (p = 0.53 and p = 0.93, respectively).

CONCLUSIONS

A short-term reversible decrease in macular electrical activity without any structural changes seems to occur after accelerated CXL in patients with progressive keratoconus. The return of macular response to the preoperative values shows the safety of the CXL protocol.

[Operative techniques for surgical treatment of primary and recurrent pterygia]

Surgical treatment of pterygia is indicated when there is a reduction of visual acuity secondary to the development of irregular astigmatism and an (impending) obscuration of the visual axis by the tumor. Poor cosmetic appearance and an insufficient corneal lubrication are more rare indications. The most popular surgical technique in this country appears to be a free conjunctival autograft which, depending on the priority of the surgeon, is combined with adjunctive antimetabolite therapy applied either in primary or recurrent cases. A simultaneous transplantation of conjunctival and limbal stem cell autografts is an excellent method to be considered particularly in cases of recurrent pterygia. In the case of non-existing healthy autologous tissue the resection bed can be covered by preserved amniotic membrane. A lamellar sectorial corneal graft might become necessary if there is a deep corneal defect. The well established technique of suturing the graft has been replaced by fibrin glue in some surgical centers.

Mutations in FRMD7, a newly identified member of the FERM family, cause X-linked idiopathic congenital nystagmus

Idiopathic congenital nystagmus is characterized by involuntary, periodic, predominantly horizontal oscillations of both eyes. We identified 22 mutations in FRMD7 in 26 families with X-linked idiopathic congenital nystagmus. Screening of 42 singleton cases of idiopathic congenital nystagmus (28 male, 14 females) yielded three mutations (7%). We found restricted expression of FRMD7 in human embryonic brain and developing neural retina, suggesting a specific role in the control of eye movement and gaze stability.

Surgery for nystagmus related head turn: Kestenbaum procedure and artificial divergence

PURPOSE

An abnormal head posture adopted to reduce a nystagmus can be treated by Kestenbaum surgery or by creating an exodeviation which is compensated by convergence (artificial divergence). We evaluated the effects of Kestenbaum surgery and artificial divergence surgery in a retrospective study.

METHODS

Seventy-eight patients who received surgery for horizontal head turn (HT) due to nystagmus were included in the study. Exclusion criteria were previous extraocular muscle surgery, strabismus, lack of binocular vision, and cerebral disease. The millimetres of surgery and the findings before and 3 months after operation [HT, binocular visual acuity (VA), binocular vision (BV)] were evaluated. The patients were divided into three groups: the Kestenbaum group, the artificial divergence group, and the artificial divergence plus Kestenbaum group.

RESULTS

Of the 78 patients, aged 3-68 years, 52 had HT to the left side and 47 were male. In the Kestenbaum group (n=31), the median (10% and 90% quantile) HT was 30 degrees (range 20-40 degrees). A total of 28 mm (range 20-40 mm) surgery reduced the HT to 10 degrees (0-30 degrees). The efficacy of surgery was 1.4 degrees HT reduction per millimetre surgery on one eye (range 0.4-2.5 degrees). Four patients received further surgery. In the artificial divergence group (n=27), 10 mm (range 7-12 mm) surgery reduced the HT of 30 degrees (range 25-40 degrees) to 5 degrees (range 0-20 degrees). Seven patients received further surgery. In the artificial divergence plus Kestenbaum group (n=20), the HT was 30 degrees (range 25-40 degrees). A total of 29 mm (range 21-37 mm) surgery reduced the HT to 7 degrees (range -5 degrees to 15 degrees). No further surgery was performed. Postoperatively, the maximum VA and BV was available without large HT, but an increase in the absolute VA and BV could not be proved.

CONCLUSION

Artificial divergence is preferable or should be combined with Kestenbaum surgery, if possible. Kestenbaum surgery alone has an effect/dose ratio similar to recess-resect surgery for strabismus. Thus, to correct x degrees HT, 2/3x mm surgery on each eye is adequate.

[Congenital nystagmus: indication, results and dosage of Kestenbaum surgery in 34 patients]

BACKGROUND

Abnormal, nystagmus related head postures can be treated by Kestenbaum's procedure, if the concept of artificial divergence (Cüppers procedure) is not expected to work. In this retrospective study, we evaluated the effects of Kestenbaum surgery in order to establish dosage recommendations.

PATIENTS AND METHODS

Solely patients who received Kestenbaum surgery (maximum 3 mm dosage difference between both eyes, i.e., without additional artificial divergence) for a horizontal head turn (HT) due to nystagmus were included in this study. Exclusion criteria were previous eye muscle surgery, strabismus, lacking binocular vision, and cerebral disease. The millimetres of surgery and the pre- and 3-6 months-postoperative findings (HT and visual acuity at 5 m distance, stereopsis) were evaluated.

RESULTS

Of the 34 patients, 21 had a HT to the left side and 20 were male. The age at surgery (median, 10%- and 90%-quantile) was 7 years (4-32), the total amount of surgery 32 mm (20-40), and the preoperative HT 30 degrees (20-40). Postoperatively (n = 31), the HT amounted to 7 degrees (0-20). The reduction of HT was 67% (25-100), the efficacy of surgery 0.8 degree (0.3-1.0) per millimetre total amount of surgery on both eyes together. Four patients needed further surgery due to residual HT. Postoperatively, the maximum visual acuity was available without HT or with significantly less HT than preoperatively. Stereopsis showed a trend of improvement.

CONCLUSIONS

The Kestenbaum procedure has a dose/effect ratio similar to that of recess/resect surgery for strabismus. Due to a long term efficacy of 1.5 degrees/mm, a dosage (in millimetres) on each eye of two thirds of the HT (in degrees) can be recommended. Physiological and methodical factors (false measurements) have to be discussed as an explanation for apparently low efficacy of surgery.