Bent fabric alley cat

Bent fabric alley cat-eye (BFAC) on cornea after the surgical procedure {#Sec5}


### *Phenylephrine* {#FPar2}

The cornea becomes swollen to several millimeters in diameter. If the patient is a child, a drop of 1.5% phenylephrine, a very mild mydriatic agent, is instilled.

### *Anesthesia* {#FPar3}

After instillation of the phenylephrine, the patient is sedated, and then the puncture to instill the drug is performed.

### *Puncturing* {#FPar4}

Small-diameter (0.22 mm) 30° blade and irrigation with sterile saline are used. The angle of the blade with respect to the vertical axis of the patient is the most important factor to avoid puncture of the iris and of the anterior chamber of the eye, so that the drug is injected directly into the posterior side of the eyeball.

The drug injection point is between 1 mm and 2 mm from the corneal apex, and the amount of anesthetic is from 20 μL to 40 μL. The corneal apex is defined as the center point of the apexes of both horizontal and vertical meridian on the cornea.

The angle of the eyeball can be observed with ultrasound biomicroscopy (UBM), or by direct visual observation using a slit lamp. The corneal apex may be confirmed through UBM after the injection. The puncturing method is shown in Fig. ,[1](#Fig1){ref-type="fig"}. Fig. 1Puncturing method: **a** puncture was not performed from the corneal apex. **b** Puncture was performed from the corneal apex. Corneal apex was confirmed by ultrasound biomicroscopy after injection. Puncture depth was measured to ensure that the needle tip reaches the anterior chamber

### Follow-up {#Sec6}

After the operation, follow-up is performed at 1, 3, 6 months and 1 year. The visual acuity, intraocular pressure (IOP), anterior chamber depth, length of the anterior segment, thickness of central cornea, and iris, anterior chamber angle, and angle of posterior chamber were observed before and after operation. Visual acuity was evaluated with the ETDRS chart. IOP was measured with the Tono-pen (Tono-yama, Japan). The measurement method follows the principle of applanation tonometry. The instrument is calibrated before each use.

Central corneal thickness is measured with ultrasonic device (Quantel, RSP-10, France). Measurement principles and parameters are as follows: ultrasound wave length is 20 MHz, the depth of depth is 10 mm, and central corneal thickness is detected. The principle of measurement is the same as A-mode ultrasound, except for the difference in the location. The measurement of central cornea thickness, which is detected by ultrasound, is performed on the superior cornea of the central visual axis, which is 1 mm above the visual axis. When the distance between the surface of the cornea and the visual axis is less than 1 mm, the measurement is performed on the cornea, and the measurement of central cornea thickness in this study is performed on the superior cornea of the central visual axis. Length of the anterior segment is determined by two horizontal lines (the first one is 3.5 mm above the superior border of the iris).

Central anterior chamber depth is measured by two horizontal lines (the first one is 4 mm above the anterior chamber) when the line is perpendicular to the horizontal axis, the measurement is performed on the nasal side of the central visual axis.

2.7. Anterior Segment Biometry {#sec2.7}


The measurements of the anterior segment including axial length, central anterior chamber depth, lens thickness, and anterior chamber angle are performed using the Galilei G6 (Ziemer Ophthalmic Systems, Port, Switzerland). The principle of the instrument is that the light beam is divided into three components (two of them are divided into two separate beams and one beam into four beams), and the light beam is focused at the cornea after penetrating through the medium and is reflected by the cornea. The refraction data and corneal contour are measured by the principle of triangulation, and it does not contact the eye. The device is calibrated before each use.

Axial length is measured in millimeter using IOLMaster 500 (Zeiss, Oberkochen, Germany). It is used as a standard method and is not affected by corneal curvature. When performing the IOLMaster measurement, the patient should be supine, with both eyes undilated. Calibration is performed using the internal reference prism before each measurement. Axial length is measured using IOLMaster in the manner described above.

Central anterior chamber depth is measured in millimeter using Lenstar LS900 (Haag-Streit, 3071 Koeniz, Switzerland). The distance from the anterior surface of the cornea to the anterior chamber. The distance is measured by the principle of laser scanning, and it does not make contact with the eye. Before measuring central anterior chamber depth, the central light beam of the instrument is focused at the cornea and then reflected by the cornea. When measuring central anterior chamber depth, the patient should be in supine position. The central anterior chamber depth measurement is performed in a relaxed state, without moving the eye. When the instrument indicates a stable reading, the light beam is centered on the central part of the cornea.

Statistical Analysis


Statistical analyses were performed with SPSS 20.0 (IBM Corp., Armonk, NY, USA).

The Kolmogorov-Smirnov test was used to determine whether continuous variables were distributed normally. P-values <,0.05 were considered to indicate statistical significance. Pre-operative and post-operative results were compared using the Wilcoxon signed-rank test. *P*-values <,0.05 were considered statistically significant.



The mean age of the patients was 48.0±16.8 years, with a range of 18--75 years. The mean post-operative follow-up duration was 13.2±7.0 months, with a range of 6--29 months. The mean pre-operative spherical equivalent was --11.2±5.5 diopters (D). At the last visit, the spherical equivalent was --0.15±0.68 D.

[Table 1](#T1){ref-type="table"} shows the pre-operative and post-operative refraction values of the patients. No eyes underwent an intra-operative complication such as a vitreous loss. The post-operative visual acuity was improved in all the cases (logMAR, 0.14±0.21), but no significant difference was found between pre-operative and post-operative data ([Table 2](#T2){ref-type="table"}).


Pre-operative and post-operative refraction values of the eyes


Variables Pre-operative

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