The eye lens is known to be radiosensitive organ and catarat can be induced by relatively low dose of radiation. In the treatment of head and neck tumors, shielding blocks are frequently used to minimize dose on sensitive organs. The shielding block, which is trade of high atomic number materials (cerrobend), produce significant dose perturbations in megavoltage photos beams. The effects of these perturbations of eye shielding blocks are measured with film and ion chambers for the treatment of head and neck malignancies. Optimum parameters for the treatment are suggested.
Head ; Lens, Crystalline ; Neck

PURPOSE: To evaluate the reproducibility and accuracy of axial length and anterior chamber depth measurements from IOL Master(R). METHODS: The axial length and anterior chamber depth measurements in 30 eyes with normal crystalline lens, 30 eyes with cataract and 30 pseudophakic eyes were measured by two practitioners using IOL Master(R) followed by A-scan and Orbscan II. The reproducibility of IOL Master(R) was analyzed by comparing the results from the first and second practitioners. To evaluate the accuracy of IOL Master(R), the axial length was compared to A-scan and the anterior chamber depth was compared to A-scan and Orbscan II. RESULTS: The difference between the axial length and anterior chamber depth measurements from the two practitioners using IOL Master(R) were not statistically significant (p>0.05). The axial length of measurement from IOL Master(R) was 0.16 mm, 0.18 mm, and 0.96 mm longer than that from A-scan, in the normal, cataract and pseudophakic groups, respectively. In addition, the anterior chamber depth measurement from IOL Master(R) was significantly deeper than that from A-scan and Orbscan II (p<0.05). CONCLUSIONS: There was good reproducibility and accuracy of axial length and anterior chamber depth measurements from IOL Master(R). However, some patients who had media opacity were not measured using IOL Master(R). It is a noncontact method, which provides an alternative to A-scan.
Anterior Chamber ; Biometry* ; Cataract ; Humans ; Lens, Crystalline

PURPOSE: To compare the effectiveness and safety of the phaco prechopper technique dividing lenses into 2 or 4 pieces before phacoemulsification with the effectiveness and safety of conventional phacoemulsification during cataract surgery. METHODS: This study included 360 eyes, which were divided into 4 groups according to nuclear opacity each group was subdivided into 3 groups according to the lens extraction technique (control, dividing the lens into two pieces using a phaco prechopper, and dividing it into four pieces) (Table 1). The following parameters were compared between the groups that had the same degree of nuclear opacity: changes in the endothelial cell count and hexagonality 2 months postoperatively, phaco time as well as the total phaco energy used for the operation, and the complication rates. RESULTS: There were no intra- and post-operative complications in any group. The endothelial cell loss rate was significantly less in nuclear opacity groups 2 and 3 with the prechopper technique than in the control group. Hexagonality was significantly higher in the nuclear opacity group 3 with the prechopper technique than in the control 2 months after the operation. Phaco time was significantly less in the nuclear opacity groups 2 and 3 with the prechopper technique than in the control. Total phaco energy was significantly less in the nuclear opacity groups 2, 3, and 4 with the prechopper technique than in the control. CONCLUSIONS: Phacoemulsification using the prechopper technique is safe, resulting in significantly less endothelial cell damage, and requires less phaco time and less total phaco energy compared to those of the conventional phacoemulsification technique.
Cataract Extraction ; Endothelial Cells ; Eye ; Lens, Crystalline ; Phacoemulsification

The purpose of this report is to investigate experimentally how the corea, sclera, crystalline lens and focusing lens influence the ultrasound intensity and beam width and to find characteristic differences due to the transducer parameters; frequency and size. A time-amplitude ultrasonic diagnostic apparatus, Aloka Model SSD-2D was used with transcucers of 10 MHz and 5 MHz, 10 mm and 5 mm diameters. The metal ball, 1 mm in diameter, was served as the echo-reflecting target which was immersed in water and moved horizontally under the transducer with a micrometer screw. The distances between the transducer and the metal ball varied from 10 mm to 50 mm in 10 mm step. The amplitudes curves of the echoes so obtained were represented by relative values. In water control experiment, the nearer the metal ball from the transducer, the more irregular the curves, with multiple amplitudes maxima and minima. These irregular curves became homogeneous as the transducer moved away from the target. The multiple peak curves were more marked when measured with transducers of higher frequency and larger diameter. At the end of the near field only a single peak was found in the axial portion of the sound field. In the far field, the beam width reduced slightly due to the divergence of the beam accompanied by slight attenuation of the echo amplitudes. When the sound beam passed through the cornea and sclera, the form of the curves remained almost unchanged, but the amplitudes decreased slightly due to the absorption of the sound energy. Scleral tissue absorbed the energy more strongly then the corneal tissue. When the crystalline lens was placed under the transducer, divergence of the beam and themoderate absorption took place. This effect was more pronounced with the use of transducers of higher frequency and smaller diameter. When a focusing lens, 25 mm focal length, was attached to the transducer surface, sound beam converged to a narrow zone, followed by later scattering. These results suggest that the transducer should be selected as to the frequency and diameter according to the site of the lesion suspected and the nature of the pathology.
Absorption ; Cornea ; Lens, Crystalline ; Pathology ; Sclera ; Transducers ; Ultrasonics* ; Ultrasonography ; Water

Experiments were performed in order to investigate the absorption of the ultrasound by the ocular tissues. Transducers of 5 and 10 MHz and diameters of 5 and 10mm were used. The amplitudes of echoes reflected from the flat metallic surface were measured as the reference echo after the ultrasonic beam passed through the cornea. crystalline lens, vitreous body, outer coats of the eyeball and the whole eyeball. The crystalline lens absorbed ultrasound most strongly whereas outer coats and vitreous body absorbed modorately. The absorption by the cornea was negligibly small compared with other tissues of the eye.
Absorption* ; Cornea ; Lens, Crystalline ; Transducers ; Ultrasonics ; Ultrasonography* ; Vitreous Body

On the developmental process of the lens opacification, some preliminary evidence suggested a defect in the pump mechanism of the lens membrane as one of the triggers for the formation of lens turbidity, eventually water penetration into the lens precedes the initial phase of cataract. Above the biochemical evaluation recognized that an apparent deficiency of Na-K ATPase may be involved in the initial factor of the hereditary mouse cataract. As a matter of one more fact, it found by the technique of lens implantation that the cataract formation of this type may by based on the inductive influences in the lens, not appeared by the outside surrounding of the lens. Additionally, at the developmental process or the cataract, the physico-chemical evidence regarding the changes of three dimensional structure and the aggregation of the soluble lens proteins may be effected in the immediate turbidity phenomenon of the lens. This report which is reviewed focusing on the membrane function delineates the approach to make finding the mechanism of the cataract using the some model expriment.
Adenosine Triphosphatases ; Animals ; Cataract ; Crystallins* ; Lens, Crystalline* ; Membranes ; Mice ; Water

Trabeculectomy with mitomycin C was performed on three patients with traumatic dislocate crystalline lens and refractory secondary glaucoma, combined with pars plana vitrectomy, intravitreal phacofragmentation and scleral fixation of the IOL. Over nine months after operations, intraocular pressures were well controlled not only without any antiglaucomatous medications and special complications but also with good visual recovery in all patients . Trebeculectomy combined with pars plana vitrectomy may be useful in some patients wit hvireoretinal disease and glaucoma.
Glaucoma ; Humans ; Intraocular Pressure ; Lens, Crystalline ; Mitomycin ; Trabeculectomy* ; Vitrectomy*

PURPOSE: To determine the risk factors and incidence of cataract formation over a long-term mean follow-up of 7.5 years after type V4 implantable collamer lens (ICL) implantation. METHODS: We analyzed the preoperative, 3-month postoperative, 3-year postoperative, and last follow-up data of 228 eyes (118 patients) with mean preoperative spherical equivalent of -12.7 D and minimum postoperative follow-up of 3 years. Additionally, we determined the risk factors for cataract formation and calculated the 10.3 year cumulative cataract formation rate and 10.3 year cumulative cataract surgery rate using a survival curve. RESULTS: After type V4 ICL implantation with minimum follow-up of 3 years, the calculated 10.3 year cumulative cataract formation rate was 20% and actual cataracts developed in 34 eyes (14.9%). The 10.3 year cumulative cataract surgery rate was 12% based on a survival curve and actual cataract surgery was performed in 12 eyes (5.3%). The risk factors for cataract formation were age (odds ratio [OR] = 1.10, p = 0.00), preoperative spherical equivalent (OR = 0.90, p = 0.00), crystalline lens thickness (OR = 9.54, p = 0.00), axial length (OR = 1.33, p = 0.00), 3 months postoperative vault (OR = 0.50, p = 0.03), and existence of peripheral touch between ICL optic margin and crystalline lens at last follow-up (OR = 7.84, p = 0.00). CONCLUSIONS: We suggest one of the main risk factors for cataract formation after ICL implantation is decreased central vault and peripheral touch between ICL optic margin and crystalline lens.
Cataract* ; Follow-Up Studies* ; Incidence ; Lens, Crystalline ; Risk Factors*

Based on the Gullstrand I model eye, a simplified model eye for testing fundus imaging device is designed. The model eye can reach the following requirements:(1) The refractive characteristics of the ocular refractive tissue are simulated, and the equivalent focal length in air is 17 mm; (2) The differences between relative refractive index differences of the adjacent materials of the simplified model eye and relative refractive index differences of any adjacent two layers (cornea and aqueous humor, aqueous humor and lens, lens and vitreous body) of the Gullstrand I model eye are not more than 1%; (3) In the case of the incident aperture diameter of 3 mm, the differences of radii of the diffuse spots formed by the paraxial light and the axial light are not more than 15%; (4) The differences of angles of chief ray and tangent line of the fundus are not more than 1°; (5) In the case of the incident aperture diameter of 3 mm, the differences of MTF values of the near axis light are not more than 0.1. The simplified model eye can be expected to be used for testing fundus imaging device instead of the test method in ISO 10940:2009 Ophthalmic instruments-Fundus cameras.
Cornea ; Fundus Oculi ; Lens, Crystalline ; diagnostic imaging ; Refraction, Ocular

Internal lenticonus is a very rare morphologic abnormality of crystalline lens which has been reported in only several cases in the literature. We herein reported the clinical characteristics and surgical findings of the anterior internal lenticonus accompanied by congenital nuclear cataract. Cataract extraction accompanied with intraocular lens implantation was uneventfully performed, and a good visual outcome was achieved in this case. Viral infection during embryonal and fetal period might account for the formation of the anterior internal lenticonus and congenital nuclear cataract in our case.
Cataract Extraction ; methods ; Humans ; Lens Diseases ; surgery ; Lens Implantation, Intraocular ; methods ; Lens, Crystalline ; abnormalities ; surgery ; Male ; Middle Aged ; Visual Acuity