Calculation of tunnel incision parameters during phacoemulsification in patients with previous anterior radial keratotomy

Background. The purpose was the choice of the type of tunnel incision on the basis of mathematical calculations in cataract patients with a previous anterior radial keratotomy. Materials and methods. During the calculations, the formula for the chord length of a circle was used: L = 2R · sin(α/2), where R is the radius of the cornea, α is the angle (in degrees) between the two corneal incisions. The chord length was measured on the limbus (upper edge of the tunnel incision) and 2 mm from the limbus (lower edge of the tunnel incision). The chord 2 mm from the limbus is more important because the distance between kerato­tomy incisions at this site is smaller. From 0.4 to 1.0 mm must be added to the width of the knife blade, depending on the type of postoperative corneal healing, which will be the key to crossing the incisions. Results. The most common knives are those 2.2 mm long with a tunnel length of 2 mm. Therefore, we perform calculations based on this knife in patients with 8 and 12 keratotomy incisions and a corneal diameter of 12 mm vertically and 11 mm horizontally. In patients with 8 keratotomy incisions, a 2.2 mm knife can be used for a corneal tunnel incision, and in patients with 16 incisions, it is impossible to use a corneal tunnel. Conclusions. In cataract patients who have previously undergone anterior radial keratotomy, a special approach is needed to the choice of tunnel incision. The choice of access depends on the diameter of the cornea, the number of keratotomy incisions and the width of the knife and is calculated using the formula for the chord length of a circle.

Clinical case of diagnosis of primary open-angle glaucoma in a patient after previously performed anterior radial keratotomy

The article describes a clinical case of diagnosis and detection of primary open-angle glaucoma (POAG) in a patient after previously performed anterior dosed radial keratotomy (ADRK). The reasons that hampered the primary diagnosis of POAG in the presented patient at an outpatient appointment with an ophthalmologist were: inadequate assessment of the ratio of the state of the lenses and low vision; a falsely underestimated level of tonometric intraocular pressure (IOP), as well as the absence of an in-depth ophthalmoscopic assessment of the condition of the optic nerve head, failure to comply with the mandatory perimetric examination in such cases. It should be especially remembered that there is a high likelihood of underestimation of applanation tonometry indices after performing ADRK, therefore, the assessment of its results should be treated with caution, identifying other clinical signs characteristic of glaucoma. This will make it possible to diagnose glaucoma in time and prescribe pathogenetic treatment in a timely manner. Key words: anterior dosed radial keratotomy, primary open-angle glaucoma, intraocular pressure.

Performing corneal tunnel incision with keratotomy scars intersection in patients after radial keratotomy during phacoemulsification

Purpose. A clinical study of safety and changes of refraction during intersection of a keratotomy scar while performing the corneal tunnel incision in phacoemulsification with IOL implantation. Material and methods. The clinical study included 11 patients (19 eyes) suffering from cataract and patients with previously performed anterior radial keratotomy. A tunnel incision 2.2 mm wide was performed with the location of the scar in its center. In case of insufficient area of the corneal tissue between the scars to involve only one keratotomy scar into the tunnel incision, the adjacent scar was transected at the final stage of tunnel formation when entering the anterior chamber. The other stages of phacoemulsification were carried out in a standard way. During the operation, the state of the keratotomy scar was assessed. A day, a week and a month later after the operation, the patients underwent biomicroscopy, autorefractokeratometry, visometry with an assessment of the values of subjective and objective cylindrical correction. In order to assess the postoperative state of the keratotomy scar and the incision zone, OCT of the cornea was performed using an RTVue 100 optical coherence tomograph (Optovue, Inc, USA) in Line, Crossline, 3D cornea modes. Results. In all cases, during the operation and also the next day, biomicroscopically the cornea was transparent, there was no keratotomy scar dehiscence. There is a dynamic of the best corrected visual acuity value by 1 month after surgery and the difference between the value for subjective and objective cylinder correction as well. The next day after the operation, in all cases the keratotomy scar on the OCT scans is uniform, comparable in width, the architectonics of the tunnel incision does not differ from that of standard phacoemulsification. Conclusion. Performing a corneal tunnel incision with the beginning of the formation outside the zone of the keratotomy scar and with further intersection of the scar with the plane of the blade so that most of it is in the projection of the center of the tunnel incision, as well as the intersection of the adjacent keratotomy scar at the end of the formation of the tunnel incision when entering the anterior chamber in case of insufficient the area of the corneal tissue between the incisions is safe at all stages of phacoemulsification and in the postoperative period. Changes in the values of best corrected visual acuity over time and the difference between the values of subjective and objective cylinder correction require further study on a larger sample and using various keratometry methods. Key words: radial keratotomy, phacoemulsification, tunnel incision, intersection of the keratotomy scar, cornea optical coherence tomography.

Descemet membrane endothelial keratoplasty in a patient with iris-fixated intraocular lens and prior radial keratotomy: a case report

Background Anterior segment surgeries such as cataract surgery, intraocular lens (IOL) repositioning, and radial keratotomy (RK) may hasten endothelial dysfunction, particularly in the context of pre-existing Fuchs dystrophy, necessitating future corneal transplantation. Case presentation A 68-year-old woman with a history of RK with associated irregular astigmatism in both eyes and iris-fixated intraocular lens (IF-IOL) in the left eye presented with six months of decreased vision in the left eye. She was found to have Fuchs dystrophy and underwent DMEK surgery. She had an uncomplicated postoperative course, with uncorrected visual acuity improving to 20/20 three months after surgery. Conclusion To our knowledge, this is the first reported case of a highly successful DMEK surgery in a patient with prior RK and IF-IOL.