Natural history and predictors for progression in pediatric keratoconus.

We studied the demographic and clinical predictors associated with keratoconus progression in a pediatric population. Retrospective cohort study. We evaluated 305 eyes without previous surgeries from 168 patients, 9 to < 18 years old, and with a minimum 36-month follow-up in a hospital corneal ambulatory.

Technical notes on prism-dioptre and Prentice's rule.

Purpose: To show an alternative interpretation for prism-dioptre and access Prentice's rule accuracy.

Methods: Algebraic calculation.

Results: The prism-dioptre can be expressed as a percentage of the distance between the prism and the plane of prismatic dislocation.

Herpes simplex keratitis revisited.

The degree to which viral infection and the host's immune reaction to viral particles participate in the inflammatory process across various forms of herpetic keratitis has remained controversial. This fact has created conflicts regarding the classification of and therapeutic planning for such morbidities. This review aims to stimulate reflection on the classifications' adequacy, nomenclatures, and therapeutic approaches related to these entities.

Three-year follow-up in advanced pediatric keratoconus: thin corneas may not have pachymetry properly assessed after crosslinking.

Aim: To analyze the crosslinking (CXL) effects in pediatric keratoconus, and to identify the patients' corneal characteristics whose pachymetry could not be adequately evaluated by Scheimpflug method after procedure.

Methods: Consecutive pediatric patients with progressive keratoconus underwent CXL were included. Best-corrected visual acuity (BCVA) and spheric equivalent (SE) were measured before and after CXL.

Sagitta of ophthalmic lenses.

Purpose: To propose alternative formulas for the sagitta calculation of ophthalmic lenses.

Methods: Equation factoring.

Results: The conventional sagitta formula is algebraically inconsistent when applied to curves with direction-oriented radii.

Prescription for astigmatic ametropia revisited.

The approach to any refractive condition of the eye with regular astigmatism is more complicated than that for myopia or hyperopia alone. It requires familiarity with the complex images collectively identified as Sturm's conoid. Fortunately, only three of those play a critical role in the interpretation of ametropia with astigmatism.

Are iris mammillations correlated with keratoconus?

Purpose: To describe the presence of iris mammillations (IM) in keratoconus.

Design: Retrospective case series and literature review.

Observations: This is a retrospective case series of eight patients presenting with keratoconus and IM, who were examined between January 2016 and December 2017 in the ophthalmology outpatient clinic.

Adult-onset Buphthalmos in Down Syndrome.

Purpose: To report a peculiar case of adult-onset buphthalmos.

Methods: Review of the medical record of a 24-year-old patient with Down syndrome who developed buphthalmos in the left eye after corneal transplantation for keratoconus.

Results: In the next 2 years after surgery, the operated eye evolved with chronic anterior uveitis that led to progressive peripheral synechiae, oscillating intraocular pressure, cataract, graft failure, and buphthalmos.

Visual optics under the wavefront perspective.

Some intriguing concepts of visual optics cannot be explained by ray tracing. However, they can be clarified using wavefront formalism. Its main advantage is in the use of the concept of vergence, which is very helpful in interpreting the optical phenomena involved in the neutralization of the ametropias.

Maintenance of the corneal epithelium is carried out by germinative cells of its basal stratum and not by presumed stem cells of the limbus.

The purpose of this investigation was to analyze the proliferative behavior of rabbit corneal epithelium and establish if any particular region was preferentially involved in epithelial maintenance. [3H]-thymidine was injected intravitreally into both normal eyes and eyes with partially scraped corneal epithelium. Semithin sections of the anterior segment were evaluated by quantitative autoradiography.

Uncovering intermittent entropion.

Purpose: Intermittent entropion may go unnoticed by both patient and physician, in some instances resulting in ocular surface disorders. Unfortunately, the current work-up used to diagnose entropion is not always sufficient to uncover the problem. We present an alternative diagnostic test.

Restoration of the rabbit corneal surface after total epithelial debridement and complete limbal excision.

How is the corneal epithelium restored when all of it plus the limbus have been eliminated? This investigation explored the possibility that this may be achieved through the conjunctival epithelium. The corneal epithelium of the right eye of 12 rabbits (Oryctolagus cuniculus) was totally scraped followed by surgical excision of the limbus plus 1.0-1.

Ultraviolet analysis of donated corneas: a portable prototype.

As technology improves human vision, some procedures currently performed may be causing a decrease of the natural UV protection of the cornea. A portable dual beam system prototype was assembled for physicians for clinical studies of these effects on the corneas endowing two types of 300-400 nm evaluations: 1, regularly donated corneas and 2, simulating refractive keratectomy by corneal lamellae removal. The system performs 500 measurements/s, providing ±0.

Autoradiographic study on the regenerative capability of the epithelium lining the center of the cornea after multiple debridements of its peripheral region.

Background: The epithelium lining the center of the cornea is assumed to lack stem cells.The purpose is to investigate by autoradiography the regenerative capability of the epithelium lining the central region of the rabbit cornea following seven scrapings of its peripheral lining, during several months.

Methods: After marking the center of the cornea with a 6 mm-diameter trephine, the epithelium outside this area was scraped until reaching the corneoscleral zone.

Keratometry device for surgical support.

Background: High astigmatisms are usually induced during corneal suturing subsequent to tissue transplantation or any other surgery which involves corneal suturing. One of the reasons is that the procedure is intimately dependent on the surgeon's skill for suturing identical stitches. In order to evaluate the influence of the irregularity on suturing for the residual astigmatism, a prototype for ophthalmic surgical support has been developed.

Regeneration of the corneal epithelium after debridement of its central region: an autoradiographic study on rabbits.

Purpose: To investigate the proliferative behavior of the corneal and limbal epithelia after debridement on the central region of the rabbit cornea.

Methods: After scraping a circular epithelial area, 5 mm in diameter, in the center of the cornea, ([3]) H-thymidine ( ([3]) H-TdR) was injected intravitreally, and the rabbits killed from 1 to 49 days afterward. The cornea, together with the adjacent conjunctiva, was processed for autoradiography.

Proliferation of the vascular endothelium of the iris following total debridement of the corneal epithelium and limbal excision of rabbits.

Background: Damage to the corneal epithelium causes not only a reaction for its repair but also affects other parts of the cornea as well as different components of the anterior segment of the eye. The purpose of this investigation was to analyze the consequences, following epithelial and limbal damage, to the iris of rabbits (Oryctolagus cuniculus).

Methods: The corneal epithelium was thoroughly scraped followed by surgical excision of the limbus.

Morphological and autoradiographic studies on the corneal and limbal epithelium of rabbits.

The investigation was centered on the morphological features of the conjunctiva-cornea transition (limbus) of the rabbit eye and the proliferative behavior of its epithelium. The eyes were processed for examination with light and electron microscopy, as well as for autoradiography after intravitreal injection of [(3)H]thymidine ([(3)H]TdR). At the sites of extraocular muscle insertion, the vascularization of the stroma extended to the peripheral cornea, and the limbal epithelium was thin with its basal stratum made up by clear cuboidal cells.

[MALKS: specifications and development].

Purpose: To describe the characteristics of a new artificial anterior chamber (MALKS, Loktal, São Paulo, Brazil).

Methods: Characteristics analysis and description of a new artificial anterior chamber MALKS (Micro automated lamellar keratoplasty system).

Results: MALKS is composed of eight parts: a) artificial chamber; b) cornea's fix ring; c) nut to join the cornea's fix ring; d) rail and adjuster of lamellar diameter; e) flatteners, to pre-determine lamellar diameter; f) infusion system, that allows the digital objective peroperative control of the intracameral pressure; g) automated microkeratome, and h) marker.

Detection system for ocular refractive error measurement.

An automatic and objective system for measuring ocular refractive errors (myopia, hyperopia and astigmatism) was developed. The system consists of projecting a light target (a ring), using a diode laser (lambda = 850 nm), at the fundus of the patient's eye. The light beams scattered from the retina are submitted to an optical system and are analysed with regard to their vergence by a CCD detector (matrix).

The exact solution for the centre thickness of spectacle and contact lenses.

The available methods for the exact calculation of centre thickness presuppose that one knows simultaneously both surfaces of the lens and that the lens' power is determined afterwards. However, this approach is of secondary importance in practical situations. The issue in daily practice is the determination of the centre thickness of lenses that already have explicit vertex powers.

Addition of obliquely crossed spherocylindrical lenses.

This paper presents a three-step method for the addition of obliquely crossed spherocylinders. Contrary to other methods it does not require algorithms or complicated abstract concepts to secure the consistency of the results.

HP program for the center thickness of convex spectacle lenses.

A HP program for a quick and precise determination of the center thickness of convex spectacle lenses is presented. The program uses 150 lines of programming and 10 storage registers. With the exception of the center thickness and one of the surface powers all the other parameters must be known.