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Anti-muscarinic topical medications in children under 18 years of age may slow the worsening of myopia. These treatments include pirenzepine gel, cyclopentolate eye drops, and atropine eye drops. While these treatments were shown to be effective in slowing the progression of myopia, side effects included light sensitivity and near blur.
There are also surgical treatments for far-sightedness:
- Photorefractive keratectomy (PRK)
- Laser assisted in situ keratomileusis (LASIK)
- Refractive lens exchange (RLE)
- Laser epithelial keratomileusis (LASEK)
Scleral reinforcement surgery is aimed to cover the thinning posterior pole with a supportive material to withstand intraocular pressure and prevent further progression of the posterior staphyloma. The strain is reduced, although damage from the pathological process cannot be reversed. By stopping the progression of the disease, vision may be maintained or improved.
The simplest form of treatment for far-sightedness is the use of corrective lenses, eyeglasses or contact lenses. Eyeglasses used to correct far-sightedness have convex lenses.
Corrective lenses provide a range of vision correction, some as high as +4.0 diopter. Some with presbyopia choose varifocal or bifocal lenses to eliminate the need for a separate pair of reading glasses; specialized preparations of varifocals or bifocals usually require the services of an optometrist. Some newer bifocal or varifocal spectacle lenses attempt to correct both near and far vision with the same lens.
Contact lenses can also be used to correct the focusing loss that comes along with presbyopia. Multifocal contact lenses can be used to correct vision for both the near and the far. Some people choose contact lenses to correct one eye for near and one eye for far with a method called monovision.
Astigmatism may be corrected with eyeglasses, contact lenses, or refractive surgery. Various considerations involving eye health, refractive status, and lifestyle determine whether one option may be better than another. In those with keratoconus, certain contact lenses often enable patients to achieve better visual acuity than eyeglasses. Once only available in a rigid, gas-permeable form, toric lenses are now available also as soft lenses.
Laser eye surgery (LASIK and PRK) is successful in treating astigmatism.
How refractive errors are treated or managed depends upon the amount and severity of the condition. Those who possess mild amounts of refractive error may elect to leave the condition uncorrected, particularly if the patient is asymptomatic. For those who are symptomatic, glasses, contact lenses, refractive surgery, or a combination of the three are typically used.
Strategies being studied to slow worsening include adjusting working conditions, increasing the time children spend outdoors, and special types of contact lenses. In children special contact lenses appear to slow worsening of nearsightedness.
New surgical procedures may also provide solutions for those who do not want to wear glasses or contacts, including the implantation of accommodative intraocular lenses. INTRACOR has now been approved in Europe for treatment of both eyes (turning both corneas into multifocal lenses and so dispensing with the need for reading glasses).
Another treatment option for the correction of presbyopia in patients with emmetropia, as well as in patients with myopia, hyperopia and astigmatism is laser blended vision. This procedure uses laser refractive surgery to correct the dominant eye mainly for distance vision and the nondominant eye mainly for near vision, while the depth of field (i.e. the range of distances at which the image is in focus) of each eye is increased. As a result of the increased depth of field, the brain merges the two images, creating a blend zone, i.e. a zone which is in focus for both eyes. This allows the patient to see near, intermediate and far without glasses. Some literature also suggests the benefits achieved include the brain learning to adapt, assimilating two images, one of which is out of focus. Over time, many patients report they are unaware one eye is out of focus.
Surgically implanted corneal inlays are another treatment option for presbyopia. Corneal inlays typically are implanted in the nondominant eye to minimize impact to binocular uncorrected distance vision. They seek to improve near vision in one of three ways: changing the central refractive index, increasing the depth of focus through the use of a pinhole, and reshaping the central cornea.
The usual recommendation for those needing iseikonic correction is to wear contact lenses. The effect of vertex distance is removed and the effect of center thickness is also almost removed, meaning there is minimal and likely unnoticeable image size difference. This is a good solution for those who can tolerate contact lenses.
Treatment is done by changing the optical magnification properties of the auxiliary optics (corrective lenses). The optical magnification properties of spectacle lenses can be adjusted by changing parameters like the base curve, vertex distance, and center thickness. Contact lenses may also provide a better optical magnification to reduce the difference in image size. The difference in magnification can also be eliminated by a combination of contact lenses and glasses (creating a weak telescope system). The optimum design solution will depend on different parameters like cost, cosmetic implications, and if the patient can tolerate wearing a contact lens.
Note however that before the optics can be designed, first the aniseikonia should be known=measured. When the image disparity is astigmatic (cylindrical) and not uniform, images can appear wider, taller, or diagonally different. When the disparity appears to vary across the visual field (field-dependent aniseikonia), as may be the case with an epiretinal membrane or retinal detachment, the aniseikonia cannot fully be corrected with traditional optical techniques like standard corrective lenses. However, partial correction often improves the patient's vision comfort significantly. Little is known yet about the possibilities of using surgical intervention to correct aniseikonia.
Low order aberrations (hyperopia, Myopia and regular astigmatism), are correctable by eyeglasses, soft contact lenses and refractive surgery. Neither spectacles nor soft contact lenses nor routine keratorefractive surgery adequately corrects high order aberrations. Significant high order aberration usually requires a rigid gas-permeable contact lens for optimal visual rehabilitation.
Customized Wavefront-guided refractive corneal laser treatments are designed to reduce existing aberrations and to help prevent the creation of new aberrations. The wavefront map of the eye may be transferred to a Lasik system and enable the surgeon to treat the aberration. Perfect alignment of the treatment and the pupil on which the Wavefront is measured is required, which is usually achieved through iris feature detection. An efficient eye tracking system and small spot size laser is necessary for treatment . Wavefront customization of ablation increases the depth of ablation because additional corneal tissue must be ablated to compensate for the high order aberrations. Actual results with Wavefront guided LASIK showed that not only it cannot remove HOA but also the optical aberrations are increased. However, the amount of increase in aberrations are less than conventional Lasik. Corneal optical aberrations after photorefractive keratectomy with a larger ablation zone and a transition zone are less pronounced and more physiologic than those associated with first-generation (5 mm) ablations with no transition zone. An upcoming systematic review will seek to compare the safety and effectiveness of wavefront excimer laser refractive surgery with conventional excimer laser refractive surgery, and will measure differences in residual higher order aberrations between the two procedures.
Aspherical intraocular lenses (IOLs) have been used clinically to compensate for positive corneal spherical aberrations. Although Aspherical IOLs may give better contrast sensitivity, it is doubtful, whether they have a beneficial effect on distance visual acuity. Conventional (not Aspherical) IOLs give better depth of focus and better near vision. The reason for improved depth of focus in conventional lenses is linked to residual spherical aberration. The small improvement in depth of focus with the conventional IOLs enhances uncorrected near vision and contribute to reading ability.
Wavefront customized lenses can be used in eyeglasses. Based on Wavefront map of the eye and with the use of laser a lens is shaped to compensate for the aberrations of the eye and then put in the eyeglasses. Ultraviolet Laser can alter the refractive index of curtain lens materials such as epoxy polymer on a point by point basis in order to generate the desired refractive profile.
Wavefront customized contact lenses can theoretically correct HOA. The rotation and decentration reduces the predictability of this method.
Refractive surgery causes only minimal size differences, similar to contact lenses. In a study performed on 53 children who had amblyopia due to anisometropia, surgical correction of the anisometropia followed by strabismus surgery if required led to improved visual acuity and even to stereopsis in many of the children ("see:" Refractive surgery#Children).
In early stages of keratoconus, glasses or soft contact lenses can suffice to correct for the mild astigmatism. As the condition progresses, these may no longer provide the person with a satisfactory degree of visual acuity, and most practitioners will move to manage the condition with rigid contact lenses, known as rigid, gas-permeable, (RGP) lenses. RGP lenses provide a good level of visual correction, but do not arrest progression of the condition.
In people with keratoconus, rigid contact lenses improve vision by means of tear fluid filling the gap between the irregular corneal surface and the smooth regular inner surface of the lens, thereby creating the effect of a smoother cornea. Many specialized types of contact lenses have been developed for keratoconus, and affected people may seek out both doctors specialized in conditions of the cornea, and contact lens fitters who have experience managing people with keratoconus. The irregular cone presents a challenge and the fitter will endeavor to produce a lens with the optimal contact, stability and steepness. Some trial-and-error fitting may prove necessary.
Traditionally, contact lenses for keratoconus have been the 'hard' or RGP variety, although manufacturers have also produced specialized 'soft' or hydrophilic lenses and, most recently, silicone hydrogel lenses. A soft lens has a tendency to conform to the conical shape of the cornea, thus diminishing its effect. To counter this, hybrid lenses have been developed which are hard in the centre and encompassed by a soft skirt. However, soft or earlier generation hybrid lenses did not prove effective for every person. Early generation lenses have been discontinued. The fourth generation of hybrid lens technology has improved, giving more people an option that combines the comfort of a soft lens with the visual acuity of an RGP lens.
Treatment of strabismic or anisometropic amblyopia consists of correcting the optical deficit (wearing the necessary spectacle prescription) and often forcing use of the amblyopic eye, by patching the good eye, or instilling topical atropine in the good eye, or both.
Concerning patching versus atropine, a drawback is seen in using atropine; the drops can have a side effect of creating nodules in the eye which a correctional ointment can counteract. One should also be wary of overpatching or overpenalizing the good eye when treating amblyopia, as this can create so-called "reverse amblyopia". Eye patching is usually done on a part-time schedule of about 4–6 hours a day. Treatment is continued as long as vision improves. It is not worthwhile continuing to patch for more than 6 months if no improvement continues. Treatment of individuals age 9 through to adulthood is possible through applied perceptual learning.
Deprivation amblyopia is treated by removing the opacity as soon as possible followed by patching or penalizing the good eye to encourage the use of the amblyopic eye. The earlier the treatment is initiated, the easier and faster the treatment is and the less psychologically damaging. Also, the chance of achieving 20/20 vision is greater if treatment is initiated early.
One of the German public health insurance providers, Barmer, has changed its policy to cover, as of 1 April 2014, the costs for an app for amblyopic children whose condition has so far not improved through patching. The app offers dedicated eye exercises which the patient performs while wearing an eyepatch.
When this magnification difference becomes excessive the effect can cause diplopia, suppression, disorientation, eyestrain, headache, and dizziness and balance disorders.
Medication is used for strabismus in certain circumstances. In 1989, the US FDA approved Botulinum toxin therapy for strabismus in patients over 12 years old. Most commonly used in adults, the technique is also used for treating children, in particular children affected by infantile esotropia. The toxin is injected in the stronger muscle, causing temporary and partial paralysis. The treatment may need to be repeated three to four months later once the paralysis wears off. Common side effects are double vision, droopy eyelid, overcorrection, and no effect. The side effects typically resolve also within three to four months. Botulinum toxin therapy has been reported to be similarly successful as strabismus surgery for people with binocular vision and less successful than surgery for those who have no binocular vision.
Although the best outcome is achieved if treatment is started before age 8, children older than age 12 and some adults can show improvement in the affected eye. Children from 9 to 11 who wore an eye patch and performed near-point activities (vision therapy) were four times as likely to show a two-line improvement on a standard 11-line eye chart than children with amblyopia who did not receive treatment. Adolescents aged 13 to 17 showed improvement, as well, albeit to a lesser degree than younger children. Whether such improvements are only temporary, however, is uncertain, particularly if treatment is discontinued.
Tentative evidence shows that perceptual training may be beneficial in adults.
Virtual-reality computer games where each eye receives different signals of the virtual world that the player's brain must combine to successfully play the game have shown some promise in improving both monocularity in the affected eye, as well as binocularity.
In cases of accommodative esotropia, the eyes turn inward due to the effort of focusing far-sighted eyes, and the treatment of this type of strabismus necessarily involves refractive correction, which is usually done via corrective glasses or contact lenses, and in these cases surgical alignment is considered only if such correction does not resolve the eye turn.
In case of strong anisometropia, contact lenses may be preferable to spectacles because they avoid the problem of visual disparities due to size differences (aniseikonia) which is otherwise caused by spectacles in which the refractive power is very different for the two eyes. In a few cases of strabismic children with anisometropic amblyopia, a balancing of the refractive error eyes via refractive surgery has been performed before strabismus surgery was undertaken.
Early treatment of strabismus when the person is a baby may reduce the chance of developing amblyopia and depth perception problems. However, a review of randomized controlled trials concluded that the use of corrective glasses to prevent strabismus is not supported by existing research. Most children eventually recover from amblyopia if they have had the benefit of patches and corrective glasses. Amblyopia has long been considered to remain permanent if not treated within a critical period, namely before the age of about seven years; however, recent discoveries give reason to challenge this view and to adapt the earlier notion of a critical period to account for stereopsis recovery in adults.
Eyes that remain misaligned can still develop visual problems. Although not a cure for strabismus, prism lenses can also be used to provide some temporary comfort and to prevent double vision from occurring.
The appropriate treatment for binocular diplopia will depend upon the cause of the condition producing the symptoms. Efforts must first be made to identify and treat the underlying cause of the problem. Treatment options include eye exercises, wearing an eye patch on alternative eyes, prism correction, and in more extreme situations, surgery or botulinum toxin.
If diplopia turns out to be intractable, it can be managed as last resort by obscuring part of the patient's field of view. This approach is outlined in the article on diplopia occurring in association with a condition called "horror fusionis".
In general, strabismus can be approached and treated with a variety of procedures. Depending on the individual case, treatment options include:
- Correction of refractive errors by glasses
- Prism therapy (if tolerated, to manage diplopia)
- Patching (mainly to manage amblyopia in children and diplopia in adults)
- Botulinum toxin injection
- Surgical correction
Surgical correction of the hypertropia is desired to achieve binocularity, manage diplopia and/or correct the cosmetic defect. Steps to achieve the same depend on mechanism of the hypertropia and identification of the offending muscles causing the misalignment. Various surgical procedures have been described and should be offered after careful examination of eyes, including a detailed orthoptic examination focussing on the disturbances in ocular motility and visual status. Specialty fellowship trained pediatric ophthalmologists and strabismus surgeons are best equipped to deal with these complex procedures.
The prognosis for each patient with esotropia will depend upon the origin and classification of their condition. However, in general, management will take the following course:
1. Identify and treat any underlying systemic condition.
2. Prescribe any glasses required and allow the patient time to 'settle into' them.
3. Use occlusion to treat any amblyopia present and encourage alternation.
4. Where appropriate, orthoptic exercises can be used to attempt to restore binocularity.
5. Where appropriate, prismatic correction can be used, either temporarily or permanently, to relieve symptoms of double vision.
6. In specific cases, and primarily in adult patients, botulinum toxin can be used either as a permanent therapeutic approach, or as a temporary measure to prevent contracture of muscles prior to surgery
7. Where necessary, extra-ocular muscle surgery can be undertaken to improve cosmesis and, on occasion, restore binocularity.
Most patients can be treated non-surgically with eyeglasses, or contact lenses.
The early stages of pellucid marginal degeneration may also be managed with soft contact lenses. Success has been shown with the use of rigid gas permeable contact lenses combined with over-refraction. Patients wearing contacts dont report increased problems with glare and contrast sensitivity, but it is not clear if this is due to the corneal disease, or the contact lenses themselves.
New studies found that the use of Scleral contact lens, a type of rigid gas permeable (RGP) lens, may be a good option for most patients with PMD. Most of these lenses are in the range of 15.5mm to 18.0mm in diameter. Regardless of the lens size, it is thought that the larger the RGP lens will in most cases be more comfortable then standard rigid corneal lenses, and at times more comfortable than soft lenses, regardless of the fact that it is a rigid lens. The highlight to the scleral design and the correction of eye disorders such as pellucid marginal degeneration is that vision with these types of lenses is exceptional when fit correctly.
Astigmatism, whether it is regular or irregular, is caused by some combination of external (corneal surface) and internal (posterior corneal surface, human lens, fluids, retina, and eye-brain interface) optical properties. In some people, the external optics may have the greater influence, and in other people, the internal optics may predominate. Importantly, the axes and magnitudes of external and internal astigmatism do not necessarily coincide, but it is the combination of the two that by definition determines the overall optics of the eye. The overall optics of the eye are typically expressed by a person's refraction; the contribution of the external (anterior corneal) astigmatism is measured through the use of techniques such as keratometry and corneal topography. One method analyzes vectors for planning refractive surgery such that the surgery is apportioned optimally between both the refractive and topographic components.