The theory and art of corneal cross-linking

Before the discovery of corneal cross-linking (CXL), patients with keratoconus would have had to undergo corneal transplantation, or wear rigid gas permeable lenses (RGPs) that would temporarily flatten the cone, thereby improving the vision. The RGP contact lens (CL) would not however alter the corneal stability and if the keratoconus was progressive, the continued steepening of the cone would occur under the RGP CL. To date, the Siena Eye has been the largest study to investigate long term effects of standard CXL. Three hundred and sixty-three eyes were treated and monitored over 4 years, producing reliable long-term results proving long-term stability of the cornea by halting the progression of keratoconus, and proving the safety of the procedure. Traditionally, CXL requires epithelial removal prior to corneal soakage of a dextran-based 0.1% riboflavin solution, followed by exposure of ultraviolet-A (UV-A) light for 30 min with an intensity of 3 mW/cm2. A series of in vitro investigations on human and porcine corneas examined the best treatment parameters for standard CXL, such as riboflavin concentration, intensity, wavelength of UV-A light, and duration of treatment. Photochemically, CXL is achieved by the generation of chemical bonds within the corneal stroma through localized photopolymerization, strengthening the cornea whilst minimizing exposure to the surrounding structures of the eye. In vitro studies have shown that CXL has an effect on the biomechanical properties of the cornea, with an increased corneal rigidity of approximately 70%. This is a result of the creation of new chemical bonds within the stroma.     

The dilemma of color deficiency and art

No "major" painter is known to be color deficient. Are there truly no color deficient artists, or have they not been recognized? The historical literature cites criteria for recognizing color deficiency in artists, but they are hard to apply without knowing the intentions of an artist. The work and commentary of a color-deficient artist who works currently in Paris are presented as an example. He uses a limited palette of colors, based on advice from colleagues as much as his own perceptions, and he uses colors in ways that do not always fit with expectations for color deficiency. Biographies of earlier painters suggest that there were a few whose color sense was poor, but these painters used assistants to help. The color sense of others, such as the English landscape painter John Constable (1776-1837), has been questioned because of a preponderance of suspicious color, such as murky green. However, there are good reasons to doubt that Constable was color deficient. It is instructive to know how proven color deficiency has influenced an artist's style. When medical information is unavailable, the best advice for the diagnostically-inclined observer is just to enjoy the art.     

Lens junctions are communicating junctions

Lens fibers are electrically coupled with each other and directly exchange dyes and metabolites. In most cells, this form of communication is mediated by gap junctions. Lens fibers lack typical gap junctions. The lens junctions, although morphologically similar to gap junctions, differ from them structurally, chemically and immunologically. Nevertheless, recent evidence suggests that indeed lens junctions are communicating junctions. The lens junction protein, MIP26, displays structural characteristics similar to other channel proteins. Once incorporated into liposomes it forms channels permeable to molecules as heavy as 1.5 kDa. Like other communicating junctions, lens junctions assume crystalline arrays and uncouple with Ca++. The liposome incorporated channels close with Ca++ and H+ in the presence of calmodulin (CaM). Partial loss of gating competency occurs after proteolytic cleavage of the C-terminal arm of MIP26. The need for a unique type of communicating junction in lens is unclear. A possibility is that this tissue has some special cell-to-cell transport requirements, in terms of size and/or charge of permeants, not shared by coupled cells of other tissues.     

60例眶颅沟通肿瘤的诊断分析

目的探讨眶颅沟通肿瘤的临床特征、种类及诊断方法。方法选择60例手术后经病理或随访结果证实的眶颅沟通肿瘤患者,所有患者均行CT扫描,54例行MR I扫描,其中增强扫描42例。20例摄视神经管X光像。结果最常见的阳性体征是眼球突出(58/60)、眶压升高(39/60)和视力下降(36/60),最常见的症状是头痛(22/60)。较多见的眶颅沟通肿瘤是脑膜瘤(20/60)、骨纤维异常增殖症(5/60)和转移癌(5/60)。眶颅沟通肿瘤的CT、MR I扫描及视神经孔X光像有一定影像学特征。眶颅沟通途径包括:视神经管、眶上裂和眶颅交界骨壁。结论掌握眶颅沟通肿瘤的临床特征、病种分类,综合运用CT、MR I和X光等检查方法可提高诊断和鉴别诊断水平。     

The art of tackling strabismus skillfully by sparing vessels

Background:Detaching a rectus muscle irreparably destroys its ciliary artery circulation which also supplies the anterior segment of the eye.Purpose:To educate strabismus surgeons about a method of detaching a muscle without compromising anterior segment circulation.Synopsis:A limbal based conjunctival incision is made. The muscle is identified, separated from its attachments and secured with 6-0 Vicryl. The anterior ciliary vessel supplying it is isolated by making a small snip incision in the muscle capsule with delicate blunt dissection parallel to the anterior ciliary artery The muscle is detached from its original insertion. The muscle is tied to sclera at the intended point of recession. The intact anterior ciliary artery, thus will continue to function, untouched.Highlights:We recommend pre-placing the sutures in the muscle and also in the sclera at the point of reattachment to avoid possible stretching and breaking of anterior ciliary vessels at the time of muscle detachment and also to dissect the artery free from muscle several millimeters more than the intended recession in order to spare the anterior ciliary circulation in strabismus surgery.Video link: https://youtu.be/Bn050Ihu9rU     

Prevention of sympathetic ophthalmia. State of the art 1989

Ophthalmologists are daily confronted with intraocular inflammation following trauma and/or intraocular surgery. In rare cases, this may lead to the loss of visual function in both eyes, i.e. sympathetic ophthalmia (SO). In order to reduce the scope of responsible action between enucleation of the exciting eye (EE), which still has good vision, and progressive inflammation of the second eye (SE) resulting in blindness if action is delayed, a score system was established based on all SO symptoms which had become known from the literature and personal communications up the end of 1988. The score system developed by HANNE et al. allows causal differentiation between SO or uveitis of other genesis in the partner eye taking into account the prior history and findings in the EE and the occurrence of symptoms after the last accident/operation and findings in the SE.If the last eye is involved, the presence of SO should be assumed in every case where there are signs of intraocular inflammation in order to allow immediate commencement of anti-inflammatory therapy, the more so since it is known that corticosteroids and cytostatics (this also applies to cyclosporin A) can only arrest the immunopathologic processes in the initial phase of the disease.     

Note-taking and note-making: The ever-cherished art!

In the medical field where the volume of information to be studied and reproduced is enormous, note taking and note making becomes an integral part of an effective learning process. Not only does it simplify the learning process, it also eases last minute revision and improves presentation skills in examinations. Knowing when and where to begin taking notes, which topics to take notes on, and how to take notes is crucial before investing one’s quality time. Restructuring a content into a table, flowchart, or an illustrative figure depicts your understanding and hard work. It can fetch more marks and save time during examination. It becomes a prerequisite to attain guaranteed success.