Refractive error occurs when light entering the eye does not focus correctly on the retina. This category covers myopia, hyperopia, astigmatism, presbyopia, glasses, contact lenses, and refractive procedures.
32 English articles
Accommodative insufficiency is a condition in which accommodative power is lower than expected for age, while ill-sustained accommodation is a condition in which repeated measurements show recession of the near point. With the increase in VDT work, it is also increasing in young people, and environmental improvement and appropriate spectacle prescription are the basis of treatment.
Accommodative spasm (pseudomyopia) is a condition in which excessive tension of the ciliary muscle causes transient myopia. Prolonged VDT work or near work are the main triggers. Differential diagnosis by cycloplegic refraction and environmental improvement with appropriate spectacle prescription are the basis of treatment.
Aniseikonia is a condition where the size or shape of the retinal image differs between the two eyes. When it exceeds 5%, it can cause eye strain, and when it exceeds 7%, fusion becomes impossible. This article explains diagnostic methods and selection of correction methods.
Anisometropia is a condition in which there is a difference in refractive power between the two eyes. This article covers early detection and treatment of anisometropic amblyopia, selection of correction methods (Knapp's law), and refractive surgery for anisometropia in adults.
Asthenopia is a nonspecific syndrome involving multiple factors such as refractive error, ocular misalignment, accommodative dysfunction, dry eye, and VDT work. Meta-analysis shows a prevalence of 51%, reaching 90% among digital device users. Proper spectacle prescription and environmental improvement are the mainstays of treatment.
Astigmatism is a refractive error caused by differences in refractive power along the meridians of the cornea or lens. This article explains the classification into regular and irregular astigmatism, diagnostic methods, and correction with glasses, contact lenses, refractive surgery, and toric IOLs.
Contact lens intolerance is a general term for a condition in which ocular surface disorders caused by contact lens wear become chronic, making continued lens wear difficult. Diagnosis is key by estimating the cause based on fluorescein staining patterns, and the mainstays of treatment are discontinuation of lens wear, improved lens care, and appropriate eye drop therapy.
Contact lens peripheral ulcer (CLPU) is a non-infectious immune-inflammatory corneal infiltration that occurs in the peripheral cornea associated with contact lens wear. It is based on the host response to bacterial components such as Staphylococcus aureus. This article systematically explains the differentiation from microbial keratitis, discontinuation of contact lenses, use of antibiotic eye drops, and management with low-concentration steroids.
Contact lens-induced acute red eye (CLARE) is a non-infectious inflammatory reaction characterized by acute onset of hyperemia, pain, and corneal infiltration during or after contact lens wear (especially overnight extended wear). The most important step is to differentiate it from infectious keratitis. Immediate discontinuation of contact lens use and steroid eye drops are the mainstays of treatment.
This article explains the definition, causes, diagnosis, and treatment of dry eye induced by contact lens (CL) wear (CLIDE). Based on the Dry Eye Clinical Practice Guidelines (Jpn J Ophthalmol 2019), TFOS DEWS III treatment algorithm, and TFOS Lifestyle report, it comprehensively describes tear film-oriented diagnosis (TFOD), tear film-oriented treatment (TFOT), CL material changes, and care improvements.
Convergence insufficiency (CI) is a binocular vision disorder in which the ability to turn both eyes inward for near vision is reduced, causing eye strain, double vision, and headaches. Convergence training and prism glasses are the main treatments, but if accommodative insufficiency is also present, environmental improvements and appropriate spectacle prescription should be prioritized.
Corneal warpage is a change in corneal shape caused by mechanical compression and hypoxia due to long-term wear of contact lenses (especially hard CLs). It becomes an issue during screening before refractive surgery, and confirming shape stability after discontinuing CL use is key to evaluating surgical eligibility. Differentiation from intentional warpage due to orthokeratology is also important.
Ectasia after refractive surgery (iatrogenic keratectasia) is a serious complication in which the corneal stroma progressively thins and steepens after LASIK, PRK, or SMILE. The prevalence is highest with LASIK at 90 per 100,000 eyes. Early intervention with corneal cross-linking is effective in halting progression.
Comprehensive explanation of post-refractive surgery ectasia (iatrogenic keratectasia), including its definition, risk factors, preoperative screening, diagnostic criteria, treatment (corneal cross-linking), pathophysiology, and its effect on IOL power calculation. LASIK prevalence: 90 per 100,000 eyes, safety threshold of RST ≥280 μm, importance of early CXL intervention.
This article explains the indications, prescription, fitting, and complication management of rigid gas permeable (RGP/hard) contact lenses for keratoconus. It provides a practical, detailed description including base curve selection using BFS values from anterior segment OCT (Itoi Method), fluorescein pattern evaluation, and criteria for transitioning to scleral lenses.
Hyperopia is a refractive error in which parallel light rays focus behind the retina. This article covers detection of latent hyperopia, its association with accommodative esotropia and amblyopia, and the importance of early correction in children.
LASIK flap complications is a general term for structural, inflammatory, and infectious disorders associated with flap creation, repositioning, and postoperative course in LASIK surgery. This article explains the classification, diagnosis, and management of DLK, flap displacement, epithelial ingrowth, free cap, buttonhole, and others.
Low-dose atropine eye drops (Rijusea® Mini Ophthalmic Solution 0.025%) is the first domestically approved treatment for myopia progression control in Japan in 2024. By antagonizing muscarinic receptors, it suppresses axial elongation and inhibits myopia progression by approximately 50% while minimizing side effects.
Monovision is a method to compensate for presbyopia by correcting one eye for distance and the other for near vision. This article details its application with contact lenses, LASIK, and cataract IOLs, dominant eye setting, effects on stereopsis, and the trial wear procedure.
Multifocal (bifocal/progressive) contact lenses are contact lenses designed primarily for presbyopia correction, integrating multiple focal points for distance and near vision into a single lens. This article explains the differences in design (concentric, EDOF, HCL), actual prescription procedures, selection of candidates, and management of complications.
Myopia is a refractive error in which the refractive power is excessive relative to the axial length, resulting in decreased distance vision. This article provides a comprehensive explanation from simple myopia to pathological myopia, including the latest evidence for myopia progression control treatment including low-concentration atropine eye drops (Rijusea® Mini 0.025%).
Orthokeratology (OK) is a treatment that uses specially designed hard contact lenses worn overnight to reshape the cornea, restoring uncorrected visual acuity and slowing myopia progression in children. This article explains indications, prescribing procedures, safety management, and combination with low-concentration atropine.
Phakic intraocular lens (ICL) is a refractive surgery that corrects myopia and astigmatism by inserting a collamer lens into the posterior chamber while preserving the natural crystalline lens. It is mainly indicated for myopia of 6D or more, does not involve corneal ablation, and offers excellent reversibility. The central hole design of the EVO ICL eliminates the need for iridotomy, further improving safety.
This article explains the classification, indications, preoperative evaluation, surgical techniques, and complication management of phakic intraocular lenses (phakic IOLs). Focusing on ICL (EVO ICL), it details criteria based on the Japanese Ophthalmological Society guidelines, including age range 21-45 years and correction amount of 6 diopters or more.
This article explains the definition, mechanism (corneal nerve transection), risk comparison by surgical technique, diagnosis, and treatment (TFOD/TFOT, punctal plugs, IPL) of dry eye that occurs after refractive surgeries such as LASIK, PRK, and SMILE. It also covers preoperative screening. The latest information is based on the Dry Eye Clinical Practice Guidelines (Journal of Japanese Ophthalmological Society 2019) and TFOS DEWS III (2025).
Presbyopia is a condition in which the lens hardens with age, reducing accommodative power and making near vision difficult. This article explains correction methods using progressive addition lenses, bifocal contact lenses, and multifocal IOLs.
Smartphone presbyopia is a common term for reduced accommodative function due to prolonged use of near-distance devices such as smartphones. It is formally classified as accommodative spasm or technostress eye syndrome, and the basic treatment includes environmental improvement, appropriate spectacle prescription, and instillation of cycloplegic eye drops.
SMILE surgery (small incision lenticule extraction) is a refractive surgery that uses only a femtosecond laser to create and extract a corneal stromal lenticule to correct myopia and myopic astigmatism. It is characterized by no flap creation and preservation of corneal nerves. Indications, surgical technique, and complication management are explained.