OPTM3233 Notes.pdf

OPTM3233 Notes Wk 1 Lecture 1 - Child Development ○ Types of Abnormal Development – Not Exhaustive - Learning difficulty – errors of copying and reproduction - Language and speech disorders - Delayed cognitive development - Autism spectrum disorde...

OPTM3233 Notes Wk 1 Lecture 1 - Child Development ○ Types of Abnormal Development – Not Exhaustive - Learning difficulty – errors of copying and reproduction - Language and speech disorders - Delayed cognitive development - Autism spectrum disorder - Attention Deficit Disorder - Stuttering - Tourette’s ○ Physical Development: Typical Development Patterns - Gross motor movements usually develop before fine motor movements due to the cephalocaudal and proximodistal developmental patterns. - Cephalocaudal Sequence: The ‘top-to-down’ development of the human body. The head and brain develop first. For example, the foetus head/body ratio is about 50%; 20- 30% at birth and 6% in an adult. Therefore, a child’s first motor skill (under cognitive control) is the control of their head and neck, before using their upper limbs to grab objects, abdomen to sit and finally lower limbs to walk. - Proximodistal Sequence: The secondary ‘centre-to-outwards’ growth pattern, from the trunk of the body to the arms and legs. This occurs from 5 months of gestation to birth and beyond. Infants gain control of their torso, limbs, and then finally fingers, which reflects the sequence of posture, gross, then fine motor control ○ Growth and Development Patterns - Child development is assessed on levels of gross and fine motor, cognitive, perceptual and social skills - Developmental milestones can also be used to detect when a developmental delay is occurring for a child when they don’t follow the expected norms. - Development can be charted by: 1. Chronological ages and stages 2. Process orientated approach - Screening tests can be performed. These compare the child’s development to accepted norms, identifying their strengths and weaknesses. E.g., The Bayley scales of infant development (1 to 42 months of age) through developmental play tasks. This method looks at all facets of child. ○ Common Facets of Child Development - Age: 0-4 months; 4-8 months; 8-12 months; 1-2 years; 2-3 years; 3-5 years - Physical - Normal body development, e.g., height, weight, walking, eye hand coordination - Social – Interactions with others - Emotional – Normal patterns of responses to situations - Cognitive – Problem solve and reasoning - Language – Communication and language use, reading ○ Brain Development: Cognitive Norms ○ Language Norms ○ Developmental Delay - When a child’s normal developmental pattern is delayed or distorted. They may hinder the future development of advanced skills and processes. - Delays can be transient or persistent and are affected by various factors such as environmental or child-rearing factors, including the duration and type of stimuli and experiences. - Early detection, referral and intervention is necessary to minimise long term effects and potentially achieve complete rehabilitation.  ○ Assessment of Development - Checklists and observations – SOVS checklist - Tests with established norms, and experienced practitioners to administer tests - Bayley Scales of Infant and Toddler Development - Battery of 5 tests/Scales: Adaptive Behaviour, Cognitive, Language, Motor, Social-Emotional - Scores can be standardised, and compared to norms - Cut off scores allow for diagnosis ○ Bayley Scales - Assesses cognitive development usually by psychologists. Lecture 2 - Theories of Learning, Cognition and Memory ○ Cognition - Mental processes in which learning occurs, memories created and the active process of acquiring knowledge through understanding and thought. ○ Learning Theories Historical - Original Sin: children were born as innately evil beings. - Tabula Rasa: child’s experiences determine their characteristics as an adult. - Innate Goodness: children are inherently good and should not be brought up with too much parental constraint. - Freud’s Psycho-sexual Theory of Development: formation of adult characteristics is shaped by early life experiences and relationship with parents.  Learning - The acquisition of new knowledge and memories - Formation of new connections between neurons in the brain - Hebbian Learning – Neurons that fire together have strengthened weighting - Long term potentiation – A strengthening of synapses based on recent patterns of activation. Increase in the number of receptors and neurotransmitter activations Non-Associative Learning - Low level/order learning. - Habituation - Learning that involves a reduction in the frequency/extent of behaviour due to the repeated presentation of a non-associated stimulus. - Initial response – large response, but decreases with time as the animal learns that the stimulus is non threatening. - Sensitisation: Learning that involves an increase in the frequency/extent of behaviour due to the presence of a non-associated stimulus that is usually noxious or elicits pain or considered dangerous. Associative Learning - A learning process in which an association is made between two stimuli or a stimulus and behaviour. A primary mechanism for learning. - Classical Conditioning (Pavlovian condition – When a novel stimulus is associated with a reflex response). - Operant Conditioning: When a particular behaviour is reinforced through reward or punishment. Classical Conditioning - A process by which a behavioural response is associated with a previously novel stimulus. - The process of learning occurs through repeated pairings of a Conditioned Stimulus (CS) and an Unconditioned Stimulus (UCS) that elicits an innate reflex/behaviour. - After learning the conditioned stimulus alone can elicit the behaviour – Conditioned Response (CR) - The CS facilitates behaviour because it is used to signal or predict the UCS. - Forward Conditioning – When the CS precedes the UCS – Increasing behaviour - Backward Conditioning – When the CS follows the UCS – Decrease in behaviour as the CS signals the cessation of the UCS - Extinction – The CR is reduced or returns to baseline after repeated presentation of the CS without reward  Operant Conditioning - Learning of behaviour that is driven by its consequences. Learning is largely driven by reinforcement. - Positive Reinforcement - A particular behaviour is strengthened if the outcomes of that behaviour is positive - Negative Reinforcement - A particular behaviour is strengthened if it reduces/stops a negative event. - The strength of a particular behaviour is governed by its consequences. B.F. Skinner: Operant conditioning and the Skinner box - A means of studying associative learning behaviour in animals - Animal placed in a box in which a lever must be pressed to release food. - Through trial and error the animal learns that pressing the lever releases food. - This behaviour increases because of its consequences – the delivery of food. – Positive reinforcement - Stopping the release of food will result in behaviour extinction - Another scenario: A loud sound is played which is uncomfortable. A lever press will turn the sound off. Lever pressing is strengthened as it reduces a negative event – Negative reinforcement Punishment and Extinction of Behaviour - A reduction in behaviour due to the occurrence of an adverse event. E.g., threatening violence if a particular behaviour is performed. - A behaviour is reduced to avoid its consequences which is usually unpleasant - Positive Punishment - When a behaviour produces a stimulus/event which reduces the strength of that behaviour. E.g., shouting at someone - Negative Punishment - When a behaviour produces the removal of a stimulus which reduces the strength of that behaviour. E.g., removing a toy from a misbehaving child Learning Through Play and Observation - Learning can be non associative or associative, but also acquired through observing others. - Learning through demonstrations and imitation and copying. But not reward oriented! - Albert Bandura – Social learning experiments. - The bobo doll and learning behaviour. ○ Piaget Cognitive Development Model - A process in which humans develop cognitive abilities and mental processes of reason, intelligence and inference. - Development through play and environmental interactions at the early stages of life. Development is characterised by a number of stages: ➔ Sensorimotor (0 - 2 years): Initial dependence on reflects and innate behaviours. Learning of motor coordination and sensory curiosity. Language limited to demands or categorisation. The concept of object permanence ➔ Preoperational (2 - 7 years): Development of symbolic thinking, language syntax and grammar, imagination and intuition. Development of conservation. During this stage, the child is egocentric; cannot put themselves in others shoes. ➔ Concrete Operations (7 - 11 years): Concepts attached to concrete operations. Notions of time, space and quantity are understood and applied ➔ Formal Operations (11+ years): Theoretical, hypothetical and counterfactual thinking. Abstract and logical reasoning and planning become possible. Concepts learnt in one context can be applied to another Piaget Cognitive Development Theory Tasks - Object Permanence: The concept that an object persists even when it is not visible. ○ Memory - A process in which information and knowledge is coded, stored and retrieved. - Neural coding of information, knowledge, skills and experiences that is useful to a person. - Basis for behaviour and fundamentally defines who we are. Brain Areas: The Hippocampus - Internal brain structure within the temporal lobes - Hippocampus - Structure that is integral to the formation of memories (particularly long term memory). Not the centre for memory, but important for memory formation.  Models of Memory: Atkinson & Shiffrin Model ○ Long Term Memory Explicit - Explicit Memory - Conscious process in which previously stored memories and (Conscious) information is actively recalled e.g., Meetings times, facts, occasions, events. Memory ➔ Episodic Memory - Memory of actual events and occasion; Flash Bulb memory, Autobiographical (memory of events that relate to the person). ➔ Semantic Memory – General knowledge and facts; The case of the savants – Evidence of extraordinary recall Implicit - Implicit Memory - The process in which prior experience aids a current task without (Unconscious) conscious awareness or recall of previous events. Memory ➔ Priming - An improvement in task performance from prior exposure to a related stimulus. Implicit inferential memory from an impoverished stimulus. Prior exposure to a stimulus influences another stimulus, behaviour and action. Priming is commonplace in daily interactions with the world. ➔ Procedural ‘Muscle’ Memory - Implicit memory that aids in skills and expertise; Riding a bike and driving. Automatic process that unconsciously governs behaviour. Lecture 3 - CL Definitions, Terminology & Rigid Lens Design ○ Contact Lens Types - Material Hard - PMMA (polymethyl methacrylate) lenses Lenses - Original “hard” lens material - Other names: Plexiglas®, Acrylate, Perspex developed in 1940s, still used today (but rarely) - Inert, optically clear, durable, easy to clean - Drawback is lack of oxygen transmissibility → usage reducing in favour of RGP lenses Rigid Gas- - Developed in 1970s Permeable - Allow gas (oxygen, carbon dioxide) transmission through lens (RGP) - Largely replacing PMMA lenses Lenses - Wide range of RGP materials with differing properties Soft Lenses Hydrogel Lenses - Developed in 1960s - Contain water in the flexible plastic (polymer) – transmit oxygen through the water - Variations in water content between lens types Silicone Hydrogel Lenses - Incorporate Si (and F) in hydrogel matrix to increase oxygen permeability - First released in 1999 (30-day lens) ○ Contact Lens Types - Ocular Surface Corneal - Partially cover the cornea only Lenses - Float on thin tear film layer, retained on eye by surface tension - Almost always made from a “rigid” lens material (RGP) Scleral - Cover the cornea, limbus and adjacent sclera, may vault the cornea, or align closely to corneal Lenses surface - Retained on eye by surface tension and eyelids - May be made from “rigid” or “soft” material - Rigid material → scleral/haptic lens - Soft material → “soft” contact lens Other Lens Types - Haptic/“scleral” lenses ➔ Scleral lens type optic haptic ➔ Made from rigid lens material (PMMA/RGP) ➔ Specialty lens only - Combination lenses ➔ Scleral lens type ➔ Central rigid lens, peripheral soft skirt ➔ Used mainly as specialty lens ○ Physical Dimensions Form - Bowl-shaped portion of a “spherical” shell Back (Concave) - Determines fit of the lens to the eye Surface - Can influence optical correction achieved – “fluid lens” between contact lens & cornea Front (Convex) -Determines optical effect of lens Surface ➔ forms new front surface to eye’s optical system ➔ large refractive index difference → refractive effect -Can influence fitting performance of the lens  ○ Lens Parameters Lens - Also termed total diameter, overall diameter, diameter, φT Diameter - Maximum external dimension (in millimetres) of the lens ➔ Rigid (corneal) lenses ≈ 8.00 to 11.00mm; < corneal diameter (≈ 11-12mm) ➔ Soft (scleral) lenses ≈ 13.00 to 15.00mm; > corneal diameter Base Curve - Also called BOZR, BCOR, BOR, PCCR, ro - BOZR = Back Optic Zone Radius - BCOR = Back Central Optic Radius - BOR = Back Optic Radius - PCCR = Posterior Central Curve Radius - Radius of curvature (in millimetres) of the central back optic zone of the lens ➔ Rigid lenses, ≈ central corneal curvature ➔ Soft lenses, flatter than central corneal curvature - Selecting BOZR for eyes with low corneal toricity - in keratometry, the flatter corneal meridian is the one with the higher number, for example 7.70 mm @ 180 & 7.60 mm @ 90, the BOZR should match the flatter meridian, which is 7.70 mm, thus, BOZR = 7.70 mm. Lens - Also called centre thickness, tc, to Thickness - Thickness of lens (in millimetres or microns) measured at the geometric centre of the back optic zone - Thickness may also be measured: ➔ at edge of lens, = edge thickness (te) ➔ at junction of curves, = junction thickness Back - Also termed BVP, lens power, F’v Vertex - Back vertex power (in dioptres) of the optic zone(s) of the lens, measured in air Power - Primarily determined by, and dependent on, the radius of curvature of the front surface of the lens ○ Contact Lens Designs Monocurve - Lens diameter, base curve, lens thickness, back vertex power Lens Back Surface - Monocurve = single curve on back surface Design - Bicurve = 1 central and 1 peripheral (flatter) curve - Tricurve = 1 central, 1 intermediate, and 1 peripheral curve - Multicurve Optic Zone - Also called BOZD, BCOD, BOD, POZD, φo Diameter - Diameter (in millimetres) of back optic zone - Larger than maximum pupil diameter - Measure under low illumination - Limited by other lens parameters (e.g. LD) - Note: radius of curvature of back optic zone = base curve of lens Peripheral - Peripheral curve specified by: Curve ➔ Peripheral curve width (PCW; mm) ➔ Peripheral curve radius of curvature (PCR; mm) - Lens diameter = OZD + (2 x PCW) - Peripheral curve radius is much flatter than central base curve ➔ i.e. PCR >> base curve (mm) Intermediate - Intermediate curve specified by: (Secondary) ➔ Intermediate curve width (ICW; mm) Curve(s) ➔ Intermediate curve radius of curvature (ICR; mm) - Lens diameter = OZD + (2 x ICW)+ (2 x PCW) - Intermediate curve radius is flatter than base curve, steeper than peripheral curve radius ➔ i.e. PCR > ICR > base curve (mm) - Note: there can be more than one intermediate curve = multicurve lens ○ Typical Lens Parameters Specifying Lens Parameters - In theory, all lens parameters, including intermediate and peripheral curve radii and widths, can be specified - Usual ordering style (example): ➔ RE: 7.80:7.70 / 8.80:8.70 / 10.80:9.20 ➔ (= BOZR:BOZD/ ICR:ICD*/ PCR:LD) ➔ BVP -3.25D ➔ tc 150μm (or 0.15mm) ➔ * ICD = intermediate curve diameter = OZD + 2 x ICW - In practice, most labs have ‘in-house’ designs. Practitioner will specify base curve, lens diameter, back vertex power, design, material, lens thickness.  - Usual ordering style (example): ➔ RE: 8.00/9.3/-3.25 ➔ tricurve, Boston XO ➔ tc 150μm (or 0.15mm) ○ Optional rigid lens features Blending of - Polishing or rounding of curve junctions Junctions - Assists with tear flow, improves comfort - Cannot be specified precisely - Degree of blend: light, moderate or heavy - Width of blended zone Front Surface +ve Lenticulation Bevel - Removed from front edge to reduce peripheral lens thickness - Used mainly for high minus lenses -ve Lenticulation - Added to thicken lens edge - Promotes lid attachment Tints Handling Tint - Advisable for novice (and experienced) wearers - Allows easy location if lens is dropped - Light grey or light blue most common - Has negligible effect on apparent eye colour Cosmetic Tint [note these are primarily available for soft lenses] - Translucent tints – darker than handling tints; can enhance natural iris colour; only truly effective on light coloured irides - Opaque tints can change iris colour R/L lens - Useful to avoid mixing up right and left lenses markings - Most common method is to use different handling tint in each eye - GREEN/GREY for RE, BLUE for LE - Can mark one lens or both, with dots or letters - Etched by hand, or laser - Markings can act as focus for deposits - May affect lens comfort, performance if too deep Fenestrations - Holes in lens, usually cut by laser - Rarely used these days - Mainly for specialty lenses, eg orthokeratology (Ortho-K) - May improve tear circulation locally - Can easily get blocked by debris - Can influence lens performance ○ Lens Parameters (Edges) Lens Edge - Vaguely defined as the extreme edge of the peripheral curve - Junction between front and back lens surfaces - Lens edge lift and shape can affect interaction with eyelid ➔ comfort ➔ lens position ➔ lens movement Edge Shape - May be rounded or blunt (Contour) - Difficult to observe, impossible to quantify Edge Lift - Distance from edge of contact lens to corneal surface, or - Distance from edge of contact lens to extension of base curve Axial Edge Lift (AEL) vs. Radial Edge Lift (REL) - AEL: measured parallel to optic axis - REL: measured along line from lens edge to centre of curvature of base curve  - AEL preferred, by convention. Typical dimensions: 40μm to 120μm. Observed vs. Calculated AEL - Observed AEL depends on peripheral corneal curvature (relationship of lens edge to corneal surface) - Calculated AEL depends on base curve, lens diameter, back surface sag (lens parameters only) ○ Lens Parameters (Back Surface Curves) - Spherical, aspheric, tangent. Aspheric Lens - Partial or complete aspheric back surface curve Designs - Designed to achieve optimum corneal alignment - May incorporate spherical central zone - Select lens on basis of: ➔ Base curve (usually 0.1mm steeper than K) ➔ Eccentricity (asphericity), in some designs ➔ e.g. e = 0.5, 0.6, 0.7 for Conocoid lens design  ➔ c.f. average cornea has eccentricity of 0.55 Tangent - Tangent refers to flat or straight line zone “Curves” - Typically used as mid-peripheral or peripheral curve - Combined with spherical (or aspheric) central optic zone - “Tangent” zone in form of truncated cone ➔ Continuous with optic zone at junction ➔ Aligns tangentially to mid-peripheral corneal surface Advantages Disadvantages - Enhanced comfort claimed due to - Accuracy in fitting essential graduated nature of intermediate ➔ Can vary cone angle to ensure zone bearing tangential alignment - Corneal distortion if intermediate bearing excessive  Wk 2 Lecture 1 - Examining Children & Communication ○ Why are eye examinations for children important? - Health (BMI, cardiovascular endurance, arm strength) - Development (emotional, social, fine motor skills, object permanence, language) - Education (hyperopia associated with poor academic performance) - Poor QoL - 15% of population are