Ophthalmology: Principles of ophthalmology

Ophthalmology: Principles of ophthalmology

Introduction: what is ophthalmology?

What is ophthalmology?

Ophthalmology is a large subject for a very small organ: it is the medical and surgical care of the eye (Figures 1.1 and 1.2), the adjacent adnexal and periocular area and the visual system. It encompasses the upper and mid-face, eyebrows and eyelids, lacrimal system and orbit, as well as the globe and eye muscles, optic nerve and nervous connections all the way back to the visual cortex. Many medical conditions have ocular features as their first presentation, for example
in diabetes, cardiovascular disease, rheumatology, neurology, endocrinology and oncology. There are strong links and overlap with maxillofacial, plastic, otolaryngological, dermatology and neurosurgery. There are links with neuroradiology and pathology. Ophthalmology combines medical and surgical skills and uses minimally invasive microsurgery and lasers as well as delicate plastic surgical techniques.

Type of patients

Predominantly the very young and the elderly. Also, middle-aged patients with thyroid eye disease, diabetes or inherited disorders. Ophthalmic trauma affects particularly the young adult. Very few eye patients become ill and die. Most remain ambulatory and are seen as outpatients or have day-case surgery.

Team

General practitioners, eye casualty officers, hospital ophthalmologists, medical physicists, optometrists, orthoptists and ophthalmic nurse practitioners all collaborate in the investigation and management of ophthalmic patients.

Sub-specialties

The eye can be subdivided into several sub-specialty areas. Some ophthalmologists practice general ophthalmology alone, although most have a significant sub-specialty interest. Sub-specialties include:

  • Paediatric and strabismus (Figure 1.3)
  • Oculoplastic, lacrimal and orbital (including oncology) (Figure 1.4)
  • External eye disease, including contact lenses
  • Cornea and refractive surgery, and cataracts (Figure 1.5)
  • Glaucoma (Figure 1.6)
  • Vitreo-retinal surgery (Figure 1.7)
  • Medical retina (Figure 1.8)
  • Neuro-ophthalmology (Figure 1.9)
  • Tropical ophthalmology

Ophthalmology at medical school

and the onus is on the student to make the most of every opportunity. One should read this book prior to the attachment and use it to further reference conditions seen in clinic. Taking structured histories and becoming accustomed with using the slit lamp and direct ophthalmoscopy are the aims of the attachment. Students with keen interest can choose to do a specialist study module in ophthalmology: students with a keen interest can choose to do a specialty module in ophthalmology where they can observe, theatre, administering botulinum toxin and laser therapy and attend multi-disciplinary team meetings with the other specialties.

How to get into ophthalmology

Firstly, one must be certain that one possesses the skills to become a good ophthalmologist. Use the cataract simulator (available at the Royal College of Ophthalmologists and Moorfields Eye Hospitals) to experience the intricacies of intraocular surgery and ensure you have the hand–eye coordination to excel at this difficult skill. Ophthalmology
is an exquisitely competitive specialty, and one must ensure optimal preparation prior to selection processes. In order to get shortlisted for interviews, showing commitment is key. Undertake the microsurgical skills course at the Royal College to ensure you are able to start surgery at specialist trainee one (ST1) level. Organize a 2-week ‘taster’ programme during your foundation training, which will also afford you insight as to the daily routine of ophthalmology training. Participate in an audit project in your local trust: if you can complete the cycle and implement change to the service, this will provide the basis to present your work at meetings. Attend the local and regional teaching programme at your deanery; if you are able to present any ophthalmic cases you have seen, all the better. Although it is not compulsory, you may wish to prepare for and sit the part one Fellowship of the Royal College of Ophthalmologists (FRCOphth) examination (no clinical experience is required to take this predominantly basic science and physics examination).

Once short-listed, the interviews are a difficult step, testing a range of skills and the ability to remain composed in an unfamiliar situation. Critical appraisal, situation judgment, role-play and manual dexterity are all tested in a 90-minute marathon!

Ophthalmology is currently a run-through specialty from the ST1 level. Targets are set throughout regular intervals and include:

  • Completing the part one FRCOphth examination and 50 cataract extractions by the end of ST2.
  • Passing the refraction certificate by ST4.
  • Completing the exit exam and 300 cataract extractions by the advanced subspecialist training year.

Medical student aims

Systematic approach

The time spent in ophthalmology at the undergraduate level is very short, so a systematic approach is needed in order to ensure that the necessary skills and topics are met. Try to cover the items identified in this chapter and refer back to it as a checklist. Many students arrive at our clinics feeling daunted and underprepared due to a lack of experience
and knowledge in the field. We advise them to think of it as any other specialty: understand the anatomy, the basic physiology and the pathology. Further to that, it will be our job in clinic to introduce you to unfamiliar equipment, such as the indirect ophthalmoscope, Goldman’s tonometer, exophthalmometer and so on. We will help facilitate the examination and slowly work up your skills in order to reach a diagnosis: do not worry if at first you are unable to visualize and appreciate very little! It gets easier, especially with the help of this book.

Aims

The aim of this book is to provide a balanced understanding of clinical ophthalmology and equip the reader with the knowledge and skills to identify, treat or refer common eye disorders.

Core knowledge

A basic understanding of:

  • ocular physiology and pharmacology
  • neuro-anatomy
  • optics.

Medical student objectives

There are essential ophthalmic skills such as taking a history, useful practical skills such as putting in eye drops, things to do when you visit the eye department such as watch a visual field being done and, lastly, essential clinical topics such as the red eye.

Essential ophthalmic skills

  • Take an ophthalmic history.
  • Measure visual acuity (Figure 2.1) using Snellen and Logmar charts, with and without a pinhole.
  • Detect an abnormal pupil (Figure 2.2), such as a fixed dilated pupil, Horner’s pupil or afferent pupillary defect using a pen torch.
  • Examine the eye movements and extraocular muscle function. Detect a squint using the cover test (Figure 2.3). Differentiate between a paralytic and non-paralytic squint.
  • Examine the red reflex (Figure 2.4) and recognize leukocoria.
  • Perform a confrontation visual field test (Figure 2.5), and detect a bitemporal hemianopia and homonymous hemianopia.
  • Use a direct ophthalmoscope to (i) examine the fundus (Figure 2.6) and identify a normal disc (Figure 2.7); (ii) detect diabetic retinopathy (Figure 2.8a) and hypertensive retinopathy (Figure 2.8b); and (iii) detect papilloedema (Figure 2.9b), glaucomatous cupping of the optic nerve head (Figure 2.9a) and a pale disc with optic atrophy.
  • Recognize common ophthalmic lid conditions (e.g. benign eyelid chalazion) (Figure 2.10) and malignant eyelid basal cell carcinoma.
  • Recognize ophthalmic emergencies (e.g. acute angle closure glaucoma) (Figure 2.11) and orbital cellulitis.

Things to do when you visit the eye department

  • Attend (i) a general eye or primary eye clinic, and (ii) a specialist eye clinic.
  • Attend an eye casualty clinic.
  • Observe an orthoptist assessing ocular motility in a child or adult.
  • Observe an automated visual field test being done
  • Watch a phaco-cataract extraction operation.
  • Watch an eyelid lump being incised or excised, for example incision and curettage (I&C) of a chalazion.
  • See retinal laser treatment for diabetic retinopathy.
  • Watch an intra-ocular injection for age related macular degeneration.

Social and occupational aspects of vision

Our social and economic lives are dependent on good vision. Refractive errors remain the single most important cause of impaired vision worldwide, and they are an important and easily preventable cause of visual impairment and severe visual impairment in developing countries (Table 3.1). Simply providing good optometry services to a wider world population will go far to meet these needs. Vision 2020 aims to tackle the main causes of blindness. Reducing infective and malnutrition- related causes of blindness will also help.

Aims

  • Recognize the differing needs of emerging and developed countries
  • Know the main causes of blindness in children and adults.
  • Know the visual requirements for driving.

United Kingdom and developed industrialized countries

Approximately 1 per 1000 children are visually impaired (VI) or SVI, and they may have associated learning, hearing, speech–language or motility impairment. This can have a profound impact on education, employment and social prospects.

Although many of the causes of blindness in children are untreatable, there is much that can be done to help visual rehabilitation with low vision aids and specific educational and developmental intervention.

The major causes of childhood visual impairment include:

  • visual pathway or cerebral visual impairment
  • inherited retinal dystrophies
  • congenital cataract, microphthalmia, optic nerve atrophy and optic nerve hypoplasia.
  • retinopathy of prematurity.

Adults

The incidence and major causes of partial sight or blindness in the United Kingdom at various ages are given in this table:

Economic blindness

A visual acuity of worse than 6/12 in the better eye in adults can be considered ‘economic blindness’ as it:

  • precludes driving;
  • prevents entry into certain occupations
  • decreases ability to function in the workplace;
  • increases risk of serious morbidity;
  • increases social isolation and the risk of psychological problems, including depression; and
  • decreases overall quality of life and is associated with increased (doubling) overall risk of death.

Services and support in the United Kingdom and Ireland (children and adults)

  • National registers of partial sight and blindness. Certification as partially sighted or blind (approximately equivalent to SVI or BL) is voluntary. It is the main mechanism for ensuring access to statutory economic benefits and relevant social services. It provides national data about levels of visual impairment.
  • Statement of Educational Needs (SEN). It is a UK legal requirement to assess and regularly review the educational needs of children with SVI in a ‘Statement of Educational Needs’. Children registered blind in Ireland are assessed by the visually impaired assessment team (VICAT). The SEN or VICAT report determines the educational placement,
    support and facilities provided by the government. VI children are educated in mainstream schools with support from an advisory teacher, special visual impairment units integrated within mainstream schools, schools and colleges for the visually impaired or residential schools for children with special needs.